The EMP subwoofer, that is a really good sale right now. If you want a sub that digs low, the best affordable sub for that is the Hsu VTF2, but that would eat up a good chunk of your budget. It would leave you room in your budget for a decent pair of bookshelf speakers though, and that is a good place to start to build up a system. But if you want a whole 5.1 setup now, what I would do is jump on that EMP sale but swap out a pair of the bookshelf speakers for their E5Ti towers.