I have used PSA/DNA in the past; they have a location in North Jersey and I just made an appointment to take my things to them. I was authenticating items worth thousands of dollars, and I think I spent about $200-250 total for 5 items.
You might want to price this before you go/send your items, just to make sure you have a reasonable shot at getting your money back when you sell. I forget how they determine cost, but I think it is a simple per-item charge (which made sense for my stuff, but I don't know what your playbills are realistically worth).
Good luck!