Too much, and it's the usual sob story - bought it cheap, sold for marginally more and now the prices are way up now that I want them back.
Sequential Circuits Six Trak
Korg ER1 (still cheap but used to be super cheap)
Crumar keyboard whose name I can't remember - haven't seen another one since
I feel like there's more but it's escaping my memory
raw unedited beat tape jams - http://soundcloud.com/bluntedcircuit
I sold 2 Technics 1210 M5Gs about 2 months before it was announced that they would stop making Technics... I sold them in near mint condition for $800. I paid $400 for them.
Now not only do I wish I still had them for my own use but I could have sold them for over double that now...
My numark mixtrack pro because of how much memories I got with it
My old Pioneer CDJ500s' (the smaller ones), my DJM600 (even though i have a 900, I've no way to build up a second setup with my 1210s) and my EFX500
Traktor Scratch Pro 2.6.3, MBP 13", iPad 2 & TouchOSC, Allen & Heath Xone 1D, Pioneer DJM900, Pioneer CDJ800 x2, Technics SL1210MK2 x2, Korg MiniKP, Korg Monotron, Korg Monotron Duo