I would suggest following the recommended Omega eBay thread and also scanning through the watches offered in the private sales listings on the forum. Cheap vintage watches that beginners find listed online are usually junk that has been sitting unsold for overpriced because they are flawed, expensive, or both. If you buy a watch on eBay that was recommended on the forum, at least you know that someone vetted the watch superficially, although it may still need some expensive restoration when you receive it.