In another thread the $100 Advent was suggested as a cheap sub and the Dayton is slightly more. I have seen a lot of people recommending the Dayton, especially in the price range. Depending on budget, these are the models I have boiled down to:
Advent ASW1200 $100
Dayton SUB-120 $120
JBL E250P $240
Cadence X-Sub $250
BIC H100 $265
HSU SFT-1 $320
SVS PB10 $400
I just ordered a pair of BIC DV62si surrounds to replace my old mains that are too cumbersome that I was using for surrounds.
Lew