Betamax movies

I picked up a working Betamax VCR the other day. This is the 2nd one in the last 9 months and I sold the 1st one on eBay, so that's what I am planning to do with this one.

Now, with the player came boxes of tapes. Probably 100+. Movies, shows etc. Most are pretty dirty. The tapes themselves, that is, not what's recorded on them.

I may try to sell a bunch as one lot, looks like people have had luck doing it on eBay. I am not going to be selling the tapes one at a time unless there are some that are very valuable like some sort of collector's items/cult classics. So the question to any Betamax buffs on this forum: do you know of any specific titles that are considered valuable?