Best if you post in the "Modern Era" forum.
Anyway, yes, I think that's a good price because seller on Craiglist in my area (No. California, Bay Area) was selling a Maverick 1-12" combo, $1200. I don't recall if it included a road case but it was in excellent condition and this seller's selling point was "Its a prototype and only 79[?] made!"
I'm not certain but the prototype uses a 5AR4 rectifier tube only while the "modern" Mavericks have a switch you could select either tube or solid state rectifier.
Boy if this prototype has tone stack controls of an early Mark Series (I, II, => Fenderish like) then that would be a dream amp for me! I don't really like the interactive tone controls. Supposedly you get more versatility but to me its a bit on the learning curve while a Fenderish tone control is fairly intuitive.