If you have the time and energy. I'd recommend trying to sell them locally-post in local selling groups and theatre communities. Packing and shipping window cards is a huge hassle. Ebay will take a cut of anything you make and the shipping may make it cost prohibitive. You have to guarantee the seller receives it unscathed.
Even if you have a yard sale and sell them for $25 bucks you may net more with less hassle than selling online.
Also if you have a local flea market or antique mall, you could rent a case and display some of them and let the antique mall do the work. Again, less hassle and you just get a check.
If you are married to getting high prices for everything, I wish you a lot of luck. That will take a lot of work. If you are truly looking to get rid of them and want them to have good home, then take what you can get. It's still money.
If you dont need the money, consider donating to a local theatre company who can auction them or use them for raffle prizes.
"The sexual energy between the mother and son really concerns me!"-random woman behind me at Next to Normal
"I want to meet him after and bang him!"-random woman who exposed her breasts at Rock of Ages, referring to James Carpinello