I really like the old Rocktron stuff. The PG Ultra is a digital preamp, it's basically the same preamp as the front end of the original Chameleons and Voodu Valves (except without the tube buffer on the VV). I like them much better than the new modeling amps, better tones, IMHO, but it takes a little more work to dial in exactly what you want. But, for that price, you might be able to find an blackface Chameleon which has the same preamp with the addition of effects, not really sure what they sell for these days.
The original ProGaps, the red and grey ones, are SS analog, also great sounding preamps and can be pretty tubey sounding. I've used alot of Rocktron stuff, I've had both the PG and the Ultra, along with blackface VV and Chameleon, Intellifex and Replifex not to mention ADA MP-1s, a Kasha preamp (very sweet) and hordes of other rack stuff. I think Rocktron was way ahead of the game back in the day and the quality of the old US made stuff was great, not familiar with the new MIC stuff, but I would guess it is still up to their standards. As always, YMMV.
I've since gone back to a head and pedals, the downside to the rack stuff was that I found myself tweaking more than playing sometimes...