Where can I find the value of really old liquor?

I found a bunch of very old name brand liquor bottles in my grandmothers basement. We are pretty sure they are from the sixties and seventies. They are mine now and I was wondering where I can find if any of them are worth anything before I drink them. Some of the bottles are Jim Beam, Wild Turkey, Cutty Sark, Bacardi, Lord Calvert's, Glenlivet, Heaven Hill, Seagram's and many others. They are almost all unopened, The rest have maybe one shot missing.