GMorrisson is correct.
The only turnoff I'll have is if the item is on the Chinese coast (Shanghai, Maccau, HK, etc.) as that means they will use asian surface mail, which is 6 to 8 weeks, if you are lucky. "Air Mail" is typically DHL or Flying Tiger and will run you $30-50, and still take 7-10 days.
Also on the "don't go there" are sellers that require using Wells Fargo, Western Union, or postal Money Orders--just too many risks with all of those payment methods. And no protection for the buyer.
I have right at a thousand transactions on eBay, going back to the beginnings of eBay. I can count "bad" experiences on one hand.
Mind, research is your friend. You have to know what market prices are for a thing (you can search for "completed" auctions to see actual sale prices). Be really careful if it's "too good to be true." (a Tamiya 1/350 USS Enterprise for $10 would be TGTBT.) Never ever forget to allow for shipping as a cost. Buy It Now trumps waiting to bid. Read the Feedback. Read Negatives for sure. Check the last 5-10 Positives, too--"D_mning with faint praise" has become pretty common on positive fb.
Oh, and always bid your maximum you will pay including shipping). Never ever get into bidding wars--unless you are keen on overpaying.