Hmmm, I see a lot of them in my neck of the woods. But hunting specific issues is another story. I buy based on corny covers (and since 99.99% of them are pretty corny, that makes it easy). I tend to go 1976 or earlier, but with Archies, that's probably just the opposite of what I should be doing as the stuff from the 80's is probably harder to find.
You're right. With 37 issues in the regular series and another 13 issues or so in mini-series, they can seem plentiful but when you try to locate specific issues, it's tougher.
BV #320 is probably going to get harder to find as well. The various comic message boards have raised awareness of Cheryl as well as her more recent Archie appearances so it seems to be increasing demand.