When buying things on ebay, never pay more than you want to. Don't get carried away. Work out the most you want to pay & stick to it.
If the seller doesn't mention postage costs. Ask the question How much? otherwise you may get a nasty shock when you have to pay for your item.
Beware of buying from another country if they don't accept paypal. Sending money via your bank may end up costing more than the item you bought.
If in doubt ask a question, most sellers are more than happy to answer.