I know everyone is always chasing a bargain, so I just wanted to give a personal recommendation for the Creative Pebble Plus 2.1 speakers for those on a tight budget.
You can find them at most PC retailers for between $69 and $79 and the sound, for the price, is incredible.
The lows, mids and highs are very well balanced and the sounds from games and music will EASILY fill a room and has almost 0 distortion at max volume on most types of music and games (not that you need it at max)
You will need to use a USB wall adaptor to get the most of the speakers, but most people will already have these lying around from old phones.
The only caveat is while the bass is good, it's not super big like some other brands, so may not suit those that like listening to reallllly heavy bass tracks. For me it has just the right amount of bass, though.
A really solid buy for anyone looking.