Troll evilbay and see if you can come up with one of the Yamaha HT series amps. They change the darn things every year and the HT junkies just have to have the newest and best'est so there should be a plethora of them used.
I have the HT5920 (three years old now) and really enjoy it. The only diff between it and the current model is that it won't switch, or upconvert to, hi-def. It will, however, switch and upconvert any other kind of A/V input, including S-video, component, composite, and optical. Looks like you can pick them up for around $160-170 on ebay, including shipping (although the auctions I saw were suspiciously "overseas" looking. Search by Yamaha home theater amp and you will have plenty to choose from.
As for speaker, ditto on pretty much anything made by Yamaha. I have also found garage sales to be an excellent source of speakers. Not so much for the actual speakers but for quality cabinets, which can be had for a song if one of the speakers has bit the big one. Replacement speakers are available from several sources including Crutchfield and your local car stereo shops.
Brad