'94 Digitech Bass Whammy. Not because I liked the effect but it allowed me this year to sell it and buy an EBS MultiComp as well as a Genz Benz shuttle 3.0 8T. Never thought that would be possible.
I bought an Akai Deep Impact for $99 several years ago, back when Zzounds was blowing them out. Sold it for $500, bought a Demeter optical compressor and a few other misc things. Best purchase ever.