Need sub

I can't afford the high end equipment that many can. I purchased a used pair of Polk R40's, have a Denon DRA 37 receiver, and with the R40's only having the 5.5" drivers I feel I need more bass.

I only listen to music in the bedroom. (size 12' x 12')

Would any of you give me some direction for a sub that is not expensive ($200-250) that will fit well with what I have. Any help would be truly be appreciated. I do not want a down firing port. Thanks again. - leg
Do a search here and at Audio Asylum, there are quite a few subs available in your price range. I bought a 10" KLH sub last year for $75. It's not the greatest sub in the world, but it gets the job done in my bedroom and was eminently affordable...

Good Luck,

Look at this thread that was posted yesterday ( a few down from yours ) for ideas :
The little yamaha's do a nice job for less than $100. A little bigger/uglier are Cerwin Vega's. If you can push your budget a little, find a HSU for $250 to $300.
Shameless plug... I have a small M&K 8" sealed sub that I've replaced in my office system. I will be posting it here in the next week or so (along with the monitors). It should be a decent fit with your room. I'm asking $150. I can send you a couple of pics and links to reviews.