http://www.800paintball.com/Shop/Contro ... /SFV/30363
Psycho Ballistics Lightning, Lightning  Deluxe, or a SuperBolt for $100.
Lightning vs the Lightning Deluxe, the deluxe has a double swing trigger, while the normal has a slide trigger.  Both take normal AC upgrades.  They are full size cockers.  Required upgrade would be some form of regulator to drop the input pressure down to 200-400 psi.  You can not easily upgrade the vertical feed.  It's removable, but not threaded.  15 degree ASA.
Superbolt is a minicocker base.  It's a copy of the dye ultralight.  The back block is a p-block, and has some custom twist lock bolt.  To replace the bolt you would either need to buy a new back block, or drill a hole through it, and then purchase evo style bolts (they are just slightly shorter).  Double swing trigger, vertical ASA.  Vertical feed is threaded, so can be replaced with a different feed neck if you want.  Also requires a regulator to use.
800 paintball had a deal where you could get a lightning deluxe and a halo B loader for $150.  That's what I picked up.  Unfortunately they've now raised the price to $200 for the combo, so not as good a deal.  The lightning deluxe out of the box was pretty much timed and read to go.  I adjusted the sear to fire slightly later, and added an old WGP regulator to it.  Playing yesterday with it everything worked fine.
So if you want to fiddle with a mechanical autococker, and see how they work, etc.  Now's your chance to pick one up for $100. 
For those of you looking for a cheap sear tripping spyder clone:
http://www.paintballgateway.com/m3drcoandcol.html
$40 for a simple electro semi only model.  Pretty hard to beat.
If you have any autococker questions, not electro questions, feel free to ask.