Depends on where you are. I just spent the last two days removing 100 rockers from an old theatre. They will end up costing me about $10 a seat by the time they are cleaned and installed -- tho they were "free" from the theatre, it costs for the 25' truck, labor to help remove them, and then there's cleaning, repairing, and installation. Nothing is free.
I got the tip on these from my local cinema supplier in the PNW who was taking out this theatre's booth. You might talk to your local cinema equipment supplier -- doing biz with them makes them more receptive to your requests. If they know of a theatre being taken out and the seats are going to be bulldozed, they might send you over.
Every seat I have was taken from another theatre (often with permission). Removing and installing seats is HARD work. You might wanna look into what it coests to have a company come in and do it all. Cheaper than a hernia opperation.