Depends on the provider. There is a signifigant amount of lag involved with any wireless provider...so in general they aren't a very good idea for multiplayer games.
Some providers give you unilimited usage for 40-50 bucks a month..some charge as much as 80. Make sure you know what you're buying, and also the fact that the speed probably won't match most cable setups.
If you can get cable or DSL, you probably should.