Living and seeing cheap in Paris
Paris is a lot more do-able on a budget than most people think. You just need to know where the "bon addresses" are.
Basically anytime you venture into 11eme, 20eme and 19eme, prices fall dramatically. Do not eat near the louvre, it'd break the bank. right outside of the metro exit La Cluny there is an excellent creperie stand which you can get an awesome crepe for under 3euros, make sure you get out the exit of the musee de cluny though. drinking a coffee (mind you, an "expresso", not your crazy starbucks size coffee) au bar instead of in the salle (so drinking at the bar or sitting down in the room) will cost you significantly less (say 1 euros vs. 2!). the menu for these drinks are usually behind the bar. Water should always come for free at any restaurant, and in the st-michel area, there are more than enough touristy restaurants that offer a full 3 course 10-15 euros meals. Seriously those are not bad. If you are under 25 years old, during the weekend buy the carnet des jeunes (or passe de jeunes, i forgot!), which should cost you 3.25 euros per day for UNLIMITED travels on the metro, bus and RER and the best is- it includes zone 3!
If you fly into the orly airport, do not take the high speed orly rail, take the bus which is a few euros cheaper and gets you straight into metro denfert rochereau. However, if you fly into CDG, im pretty sure the RER is cheaper than the CDG express bus (Roissy bus), but it does take you straight to Opera area.
In each area there's a steal. Here's a few secret hiding places to check out good and cheap restaurants: metro Belleville, Place d'italie, Arts & Metier- all areas with a sizable Asian community, where usually good food and cheap supermarkets are right around. Metro strasbourg-st-denis and chateau d'eau have plenty of cheap restos as well.
Shopping in supermarkets for picnics will also be moeny-saving for you, but try to go for franprix, ED, supermarchés de paris, avoid monoprix. Weekend markets in certain areas (not all, mostly in the east. basically west of metro tuileries things get expensive) will be very cheap and offer you a wonderful glimpse into parisian lifestyle. My favourite market used to be the saturday market off of metro Avron, awesomely cheap, fresh, and very fun. Make sure you check the back part of the market where its mostly Arab vendors, and their products are cheaper.
Go also to porte de clignancourt on sundays for their famous flea market. i never managed to go there but my friends always say its fun.
Another fun area to visit is the bank of canal st martin. On a beautiful day i used to go with friends for an after-work drink and picnic, lots of little cafes, and the side near metro Jaures has a very cool student bar where you drink sitting outside.
Aim for happy hours in most parisian bars and you'll enjoy a nice beer or two.
Buy your daily grub in patisseries - baguettes will fill you up easy and cost you no more than a euro the whole piece. Or, buy a freshly made sandwich in any patisserie.
Rue du cheval blanc (i think) in bastille area is a whole street full of bars and i find their drink prices very reasonable.
If all else fails, Mickey D's does offer a dollar menu, and FREE wifi (in certain ones, not all of them. Also no plugs in restaurants, charge your laptop well before bringing it in).
Surely many will argue that people come to paris to see FRENCH CULTURE, not ASIAN culture or likewise, but after living 2 years in Paris on a 250 Euros budget (whats left after paying rent and transport), i find these areas fascinating, bursting with activity, plenty of cool things to see and lots of fun. I really miss how the moment I stepped out of my door something is happening. Either its a café with people sitting and conversing, basking in the sun or just a beautiful quiet street unfolding in front of you. I love how the city is so well connected, modern and historical at the same time. I love the way they take their time eating lunch. I love the smell of fresh bread around the corner. I don't love the high prices, I don't love the sometimes (and yes its true) snobbishness of Parisians, how blasé they are, but I do appreciate their hard-working style, and those are some of the reasons that I love Paris.