$3 for a 32 page digest sized, (~8.5"X5.5"), book, but it was photocopied, hand stapled by someone who had plenty of free time and the artists often weren't fully paid. Plus, Hirtes wasn't exactly reporting his income from these, which ended up getting him in trouble, (as he was on welfare).
As for the prices, that $3 would be about $6 in today's money. For contrast, a 32 page comic from a small publisher that is professionally printed in colour is about $4 right now.
Of course, if you want pinups, furry art is dirt cheap. Commissioning this much art of that quality could easily be done for ~$600 and that gets you exactly what you want. If you don't care exactly what you get, following a dozen decent artists on FA could get you that much every week for free, (and at a much higher quality[1]).
[1] Standards have gone up and the artists involved in this who are still active have gotten better over the years.
Base +20, DeadSoulXX -21, Anonynmous +6, QuikBasic +7