It has become old enough, that it is getting more difficult. A quick check on Ebay shows an effective price of about $30/chip.
http://www.questcomp.com has them for about $10 each (a little more for 1, a little less for more) and in stock. That's for the 44 pin PLCC. They show the DIP as in stock (5 and 8 in two categories), but it has a request a quote next to it.
I have a bunch of 53C96 on hand, which are NOT pin compatible with the 53C80. And by a "bunch" I mean 660. But they're in a sealed brick, and I'm not willing to break it open unless someone has a seriously cool use for them going. I doubt there is much use for them. They won't make a substantial improvement over the 53C80, as they're the C, not the CF 53C96. I wish I had lucked into a brick of 53CF96...