I've had my N900 on T-Mobile here in Ohio for about a year now, they provide a decent 3G service. Well, as decent as any of the various providers have seen fit to offer -- if you go any distance from the major cities or highways here, cell phone towers become mighty scarce. Only Verizon has any decent coverage, and even they get really spotty in the rougher parts of Ohio (they're practically nonexistent in the southeast corner of the state, and have gaping holes in the more rural areas elsewhere). So be warned if your university is somewhere in the hinterlands of the continent.

As to buying/selling -- I've been trying to save up enough cash to get a spare N900. So far, good used ones are going for over $200 on Ebay, and there seem to be plenty of them being sold (although a lot of them are shown as coming from Hong Kong; those seem kind of dodgy). I'm not sure how that translates into Nepal currency...