Night life is good too. Or close to après. Ski in ski out also a bonus.
Inexpensive and 3 Vallees ski accommodation don't often fit in the same sentence.
But I have had good low price deals from this company by waiting till the last minute and booking on their last minute specials. http://www.skiworld.co.uk/ they do do short stays but their core business is chalet parties. You get a room in a house or an apartment and someone comes in and cooks breakfast and dinner for the whole group. this means you have to share the dining living areas.
Meribel will be the most Brit of the resorts.
La Tania will be the cheaper and is often Ski in Ski out.
But the cheapest will be found here http://www.les3vallees.com/en/the-resorts-brides-les-bains.23.s1/ rarely ski in ski out and you may have to down load.
Well, there are loads of inexpensive accommodation, actually. Val Thorens is a well-known student destination, because of the apres-ski and club possibillities mostly. Skiing is superb.
Check out valthorens.com and remember to search accomodations with at least one spare bed room, otherwise you end up on a sleeping couch in the tiny living/kitchen. Prices vary heavlily on the preiod you travel in. Christmas holiday (Dec 19 - Jan 2), Spring Holiday (Feb 6 - 20) and Easter are the peak periods, in between and after prices of accommodations are lower.
You'll meet people in the night life facilities most likely.