Thank you Tyler, really wise words.. I'm not familiar with 16mm at all, so what means the fact that this camera doesn't have double sprockets and what does that imply?
Originally 16mm film had perforation holes on both sides, like 35mm. As sound became more standard, the 16mm format turned into single perforation, one side now used for the soundtrack. Since the 60's, almost every 16mm camera has been single perforation, but before the 60's, many cameras were still had double sprockets.
Why is this important? Well, modern film is single sprocket. Since double sprocket cameras are so old, Kodak doesn't feel it necessary to package their modern films for those cameras. You can still get double perf stock, but it's limited to black and white.
I'm not 100% certain, but I'm pretty sure the H16 Rex 1's were double sprocket for double perf film originally. I see them all the time on ebay for around the price you're discussing. Generally owners who know their cameras, will mention double or single sprocket in the advert somewhere.
400$ for a 1980's EBM, you had a really really good deal!
Twas a great deal and I've shot quite a bit with it since purchase. I do see them go for $600 on ebay, but condition unseen. At least mine I could test because I bought it from a camera show vendor.
250euros for a Rex1 + Berthiot 17-85, do you think it's a fair price?
However, as you're new to this whole thing, Giray's comment is very important. These cameras make quite a racket and are not capable of syncing to audio. So you would use this kind of camera for silent films, rather then sync sound productions.