Subwoofer for Beginner

I thought I'd experiment with a subwoofer with my Audience ClairAudient 2+2s. My room is an odd shape and bass is getting sucked out around a room divider that holds our TV. Can someone recommend a low cost small footprint (our place is small) subwoofer that would give me a taste of what a subwoofer can do? I want to see how it can work before I drop a bunch of money.