"it depends"... on several factors, the two most important being: - overall condition of the watch, originality, recently serviced? - is it complete with box/papers? I'd suggest you do an advanced search on Ebay looking for completed auctions. You can also search the sales forums here, and google for live auction results using the reference number for that watch, which is "3578.51". If you look at a site like chrono24.com you'll see prices around $12k USD... but that's what is being asked, not what they are selling for.
it's worth what someone is willing to pay for it . a quick Google search and you will have all the info you require on the snoopy.
an exemple if that can be helpful https://www.chrono24.fr/omega/speed...watch-snoopy-awards-steel-42mm--id6713343.htm