It will depend on the demand in your area. I've seen them sell (and have bought them) for as little as $350 in top shape, and for as much as $650. I've sold a couple in the top end.
Pre-Bs are nice, but you have to be willing to deal with several downsides for those guns:
1) New hi-cap mags (for the 75Bs) may not (probably won't) work in the gun. Many of the older 15-round mags will. The inside of the grips can be opened up pretty easily, so that the newer mags will work, but that'll be a needed step.
2) Some parts, like pieces in the safety mechanism of the older models, are getting very scarce, and those models can't use newer design parts in their place. Slide stops are another hard-to-replace part. A new slide stop may work, but won't necessarily lock the slide back. And, iIf you damage those original grips, be prepared to do something different. Newer grips WILL work, but will not look authentic. (Never a problem for me. I like the soft-rubber factory grips.) If you're willing to sell the waffle grips, you can probably buy some very nice custom wood grips with money left over.
3) Sights for the older pre-Bs are staked at front, and use a different dovetail at the rear. If you want different sights, you'll have to have a gunsmith do some work.
Most of the pre-Bs have great triggers, but you can get that type of trigger with a new CZ and a little gunsmith work... and still have a very good warranty. (I highly recommend the CZ Custom Shop.)
I have had MANY CZs over the years, both B and pre-B (25+?), and I just don't go the pre-B route any more. I might be seduced again, with one at a low-enough price, but I won't pay a premium because it's a pre-B.
$400-$450 might be a good offer for the one you describe, and go from there -- that's about the price you'd expect to pay for a good used "B" model.
