I am looking to start building out a nice 5.1 system over the next year or so. I am fairly set on starting out with a couple Pioneer SP-FS52s and a refurbished Denon AVR-1613 from accessories4less. I'd like to couple the floorstanders with a decent subwoofer. I am a medical student and don't have a lot of cash to spend, nor is this setup going into a huge room. I have been looking at the Dayton SUB-800/SUB-1000 and the Pioneer SW-8MK2 that matches the FS52s. I want to keep the price of the sub around $100, and get the best bang for my buck. Are these decent places to start? Any suggestions on other subs or speakers? Thanks.