from negombo you can take a train to colombo fort, it takes about 1.30 minutes but cost about nothing and is safe and you heve nice scenery and local life
the tuk-tuk from negombo to the train station costs about 200rps
silversands have a airport pick up for 1700rps from the airport and 1200 to the airport.
at the airport is easy to find a taxi,
with public transport,there is a free shuttle to averiwatte busstation, and from there busses to negombo and colombo.
Negombo railway station situated in the middle of the city. You can go to Colombo (down side) or Chilaw \ Puttalam (up side) by the train from here. It is cheaper and faster than other transports. You can find the TRAIN TIME TABLE from www.railwaynegombo.blogspot.com.
Main Bus Stop is at Greens Road, after passing the Negombo Railway Station.
One way fare to Colombo-Pettah is now SLR 41 by the Bus Number 240
Travel Time Aprx One and a Half Hour and Buses departs frequently. Red is Government and White is Private, but the fare is same.
There is Air Conditioned Mini Bus (Coaster) with same number which cost SLR 75 and takes around 45 minutes in normal traffic.
For Kandy, you can get the Bus from same place, Travel Time is around 3 and a half hour and fare for Non Air conditioned Bus is SLR 130.00 ***Last Year*** (Dropping you off at Kandy Post Office)
From Airport to Negombo Beach Side 500 Sri Lankan Rupee (Need to bargain for this price) Travel Time around 15 minutes.
Now you can just walk out of arrival hall gate to the departure to your right and get the tuk tuk from there.
I asked a tuk tuk driver for a fare from the Paradise beach Hotel up to Rodeo Bar, a distance of around 1 km maybe. Eventually a fare of 150 agreed (I know but I didn't have the energy at that point to haggle further). When I was dropped off I handed over 2 x SR 100 notes as I didn't have any 50s, and stood facing him to await my change. The driver pocketed the cash and went to drive away. I was only given my change when I challenged him.
I asked around to get a quote for a transfer to the airport. I was initially quoted SR 1500 by everybody to which I walked turned and walked away. The response to this invariably was the price immediately tumbled to SR 700 and then SR 600 with a little haggling.
A car and driver is generally the quickest and easiest way to get around in Sri Lanka but for the more adventurous you can catch a train from Negombo to just about anywhere (for next to nothing) Chilaw for example is worth a look and is an easy half or full day trip from Negombo.
Sri Lankan trains are easy to use and there is only one line north from Negombo (which goes as far as Puttalam) so it's very difficult to get lost.
Look here for times: http://www.railway.gov.lk/index.php
you can get any type of motor cycle from negombo. there are few places and you can compare the rate and bargain.
they are very friendly and they will give some riding advices too.
choose your bike and go around Sri Lanka