Before bidding, review the Terms of Sale for that specific item carefully. Ebay does not set the terms - the seller does! While it is typical that you will have 7 days to complete the transaction and that the seller will accept a deposit pending delivery, those terms are not universal. Plus, if you want the deal subject to an inspection, or expect the deposit to be refundable, discuss with the seller first and get specific answers. [In my opinion] Other than misrepresentation of the item or failure to complete the sale, Ebay isn't really on your side. They don't really care if you didn't do your homework well.
If you notice a hot-looking RV on auction but don't have time to contact the seller and get the answers you need, my advice would be "don't bid".
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL