I get to SXM from the USA, so can't help you with cheap prices from Europe. I observe, however, that AF and other French lines like Corsair seem to provide most of the service from Europe. IIRC, KLM is down to one flight a week +/-. There has been other Dutch service, but I think it went belly up in the past few weeks. I've noted newspaper reports of the Dutch-side students going to the Netherlands via AF (and Paris).
From the USA American Airlines has 3-a-day 757 from San Juan or Miami. Continental offers daily 737 service (I think). US Air has weekend 757 service.
The St. Maarten Daily Herald will keep you up to date with politics on the Durtch side, and a few things on the French side.
http://www.thedailyherald.com/ The Web version appears 5 days a week.As you may know, English is the native language of the Dutch side (Dutch is taught as a foreign language in the schools). I've never had trouble just speaking English on the French side - including a couple of visits to the hospital.
IMO, the two sides of the island are very different. The Dutch side is very American. and glitzy with BIG hotels, big casinos, Philipsburg is a tourist trap for cruise ship passengers.
The French side doesn't have huge hotels, no casinos/gambling, but more better beaches.
I've stayed a number of times at
La Plantation which is less than 10-minutes walk from the middle of Orient Beach. When you get to the beach turn right for the action, turn left for an essentially vacant 1/4 mile of beach. La Plantation is among the cheaper good hotels and all units have cooking facilities. Prices include a good buffet breakfast: bread, drink, dry cereal, fruit, fruit juice, ham, cheese, boil-youself eggs, etc.; enough so I generally don't eat lunch.
Grand Case is 10 minutes away by car and has over a dozen very good (not cheap) restaurants.
The US dollar is the de facto currency of both sides of the island used by locals and tourists alike.
You'll want a rental car. I've had problem$$$ with Thrifty on SXM. I've rented from Hertz on SXM a number of times with no problems - and they seem to have better cars. They had a Web rate that was cheaper than walkup this January.
The island is busy when the cruise passengers are loose (10am - 4 pm), but not so much so outside those hours.
More?? I was there this January.
sc