I found a local opportunity for an Engl E 4x12 vintage. My head really needs V30's to sound good and Engl seem to have a pretty good reputation. I had a kind of hard time finding good info on this cab. Would $5-600 be reasonable for this? How does it compare to more common cabs like Recto?

where are you located? $500 in one area may be a steal, but in another you'd be getting ripped off.

Engl uses a slightly diffrent V30 design, a little darker than what you would buy off the shelf.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate