Does anyone know a place were i can find all old and rare props?
Garage sales, thrift stores
There is of course no one place to find all old and rare props. EBay does have a good deal of stuff, certainly not even a large minority of older and rarer props at any one time, and some rarely, if ever. And prices for anything even moderately desirable are aspirational. But it is a place to start. Facebook Marketplace is much thinner and people aren't looking to ship. Craigslist is even thinner. Both of the latter two are very hit or miss; you are unlikely to find a particular less-common prop.
If there is something you can't find elsewhere, you might want to take a shot by posting on HalloweenForum.com, Wanted to Buy.
A word of caution: anything 10 years or older that has thinner latex (most animatronics/lifesizes) may well have latex damage. If someone really hasn't taken care of it, it will almost certainly have latex damage. And generally, once thinner latex starts to go, it is gonna go fairly rapidly.
Definitely eBay I have 3 tabs open for searches on eBay for thrashing clown Demonica and creepy rising doll
Idk i heard that Facebook market place and craigslist are the best because unlike ebay, you can search by an area
What do you think?