My dad was the AV librarian for several years before he retired from a local college. It was a long time ago now, but when those 90 minutes cassette tapes came out they seemed great. I may still have a couple around, but he stopped ordering them for use at the school because they could fail very quickly. The tape is thinner in order to get that much on the reels.

A quick glance at eBay shows 139 reel-to-reel tape recorders, most appear available for reasonable prices.

SRS