This journey happens in several steps:
1. You first need to get to the bus terminal: From Catalina la india (Carrera 11 con Calle 36 where the pocahonta-like statue is), take a bus where it's written on it "Metrocar" (double check with the driver if it goes to the Terminal). Price was 1700 pesos I believe. journey is about 45min so if you take a taxi, it will probably be expensive (min 20 000 pesos I guess)
2. Once at the bus terminal, ask a few companies there price for Santa Marta, I paid 20 000 pesos. I've been told it was cheap and it quite common to pay 25 000. The journey is about 4-5 hours.
3. From Santa Marta terminal, you can take a bus to Taganga, it's 1200 pesos I believe. Otherwise you can take a taxi and it should be around 10000 pesos (12000 at night). Journey time is around 15min.
Note that all the prices date from June 2012.
We did not stay here as most gringos do but chose to day trip from Santa Marta. This is easy to do as frequent mini-buses ply the route for a mere 1200 COP (60 cents) and take only 15 minutes. Head to Carerra 1C or 5 in Santa Marta and look for Taganga signs on passing mini-buses. Drivers will likely seek you out as if you are a gringo, they will correctly assume you are headed that way! Coming back from Taganga is equally easy as the buses come down at least part of the beach, especially the end towards the headland trail which is also a bit less crowded at sunset than in the "middle of the action" in town.
You can also arrive here directly by boat from Tayrona National Park for about 40,000 COP ($20) but this only makes sense if you are staying here rather than Santa Marta and probably doesn't work out as any quicker or cheaper than going around by bus.
It is very easy to travel between Taganga and Santa Marta with the freequent minibuses. They cost 1000 peso (July 2007) and it takes about 15 minutes from Taganga to Plaza Bolivar in Santa Marta. Sometimes the minibuses goes up the road past Casa Felipe, but sometimes they don´t.
When I arrived to Santa Marta bus terminal I took a minibus from there all the way to Taganga. The price was the same but it took about 45 minutes.
Uppdate August 2008: The minibuses still cost 1000 pesos and coming from Taganga they go along the playa and pass Plaza Bolivar in Santa Marta. But that street is now a one way street and if you are going from Santa Marta city centre back to Taganga the buses are leaving from Carretera 5 (a few blocks from the beach front).
When you arrive at the bus terminal in Santa Marta you can either get the bus to Taganga or the taxi. The bus is a 15-20 minute ride (0.50$). Taxis ask for about 4$ or more to take you to Taganga but you can negotiate. If you happen to be near the central beach of Santa Marta a taxi is is about 2,50$.
To Playa Grande you can take a boat for 2,5$ or walk for 45 minutes.
To Tayrona Park the cheapest thing to do is get the bus to Santa Marta, which locals call busetta. Tell the driver to drop you at the spot where you can catch the bus to Canaveral which is near the entrance to Tayrona Park. It is just off the center of Santa Marta and costs 2$. You don't have to go to the terminal. It will drop you at the entrance.
Tourist offices offer buses to Canaveral from your hotel for about 6$. They also have day trips to Tayrona by boat to Canaveral or Playa Crystal and back for 30$, which I think is overpriced but anyway...Generally everything in Taganga is overpriced....
There are a few tourist agencies in Taganga and Santa Marta offering diving and snorkeling and tours to Tayrona Park, to Santa Marta for a half day sightseeing, to Ciudad Perdida, even to Cartagena. Of course this is for people who are extremely short of time and are prepared to pay a substantial sum of money. Most of the sightseeing you can do by yourself. But you can use them for the Ciudad Perdida and for diving. Just shop around.
As I was going to change transport several times and cross the border I left the posada in Coro already at 6am. I found a taxi without walking too far, it was 5000 pesos to the bus terminal. At the terminal I decided to take a por puesto (shared taxi) to Maracaibo instead of the bus because it is faster. Not until 7.30 did the car get full so we could leave and about halfway we stopped to eat. The por puesto to Maracaibo was 30 000 Bs and took 3,5 hours.
As we arrived in Maracaibo I was immediately taken to another por puesto that was going to cross the border to Maicao in Colombia. It was also 30 000 Bs and it took 3 hours to Maicao. There were several police checkpoints along the way to the border. As we came to the first police the driver turned around and asked for money. I think he first asked for money from me and one of the man (but I‘m not sure he wanted me to pay as well). I had no intention to pay but only took out my passport from the bag. The man paid 5000 Bs and did so at several occasions. I soon realised he was travelling without a passport (I have later heard that is quite common at this border). Before leaving Venezuela you have to pay the departure tax, which is 37 500 Bs (July 2007). You must also leave the immigration form (if you have one from the airplane) or fill in a new form.
At the Colombian side everything was very quick.
From Maicao I took a bus to Santa Marta. It was leaving half an hour after I had arrived and it took 4,5 hours to Santa Marta. The bus ticket was 20 000 pesos.
Outside the terminal in Santa Marta there are minibuses going to the city centre and Taganga for 1000 pesos. It took 45 minutes to Taganga as the minibus first drove through Santa Marta. It was after 7pm and dark when I arrived to Taganga, but there are a lot of people out at that time who you can ask for direction.
Knowing it takes a very long time to go from Taganga to the terminal in Santa Marta I asked in the reception of Casa Felipe for a taxi. They told me that a taxi to the terminal is 8000 pesos when they call. I didn´t ask the taxidriver and he wanted to have 10 000 pesos as we arrived to the terminal.
At once I entered the terminal I was met by people who asked me where to go. I went to a company, Transportes La Costena, which had a bus leaving within 10 minutes. The bus was quite small with aircondition (not too cold). There are no seat numbers and I was happy to find an empty seat by the window (on the right side where the sea is). The ticket was 20 000 pesos (July 2007) and the journey took a little more than 4 hours.
The terminal in Cartagena is far outside the city. There are buses going to the city centre for 1500 pesos, but I desided to take a taxi. Outside the terminal where all the taxis are there is a big sign saying how much it cost to go by taxi to different parts of the city. To Getsemani it was 9500 pesos.
There are several mini-vans that ply the roads between Sta Marta to Taganga for a few pesos (check the sign on the mini-bus and make sure it says "Taganga" in it or ask a local to point you on the write one). It's really dirt cheap. Alternatively, you can take a taxi :).
Getting to Taganga is easy. Take a bus to Santa Marta, then a collectivo (mini bus) from the terminal to the centre, then another (K11, taganga is marked on a board in the windscreen) to Taganga. All collectivos cost 700pesos regardless of distance travelled.