Cheap, vintage, discrete spring reverbs.

I almost hate to do this because this seems like one of the few things left to discover, but back in the late 60s, Pioneer and Sansui were making spring reverb units for home stereos. I just snagged one of the Pioneer SR202s for $40, and have a bid in on a Sansui (so don't bid, yo!). This era of home audio gear is typically more robust than much of the pro-sumer stuff out today, and there's just a great vibe about it all. Search youtube to hear some rad stuff, and you'll see how cool and inexpensive these are.