Ebay is great only because of the high volume of transactions and the feedback system.

Best advice is

1. buy only from sellers that take Paypal credit cards, and

2. have a feedback rating of  99 or better. Even then, good sellers go bad.

3. Make sure the feedback is from both buys and sells and the items are more than one penny.

4. Check the service after the sale (deduced from feedback). Sometimes the lowest priced seller (item and shipping/handling) is not the best.  You want a hassle free sale. Time is money.  Why worry? Buy from a reputable seller.

5. Avoid items that are expensive to return. Sometimes a local Wal-mart is a more viable option. They are better about returns and local.

Here on Ebay...there is little by means of the buyer protection. Ebay charges $25 to investigate. Anything under $25 is not protected.

Paypal requires the seller to delivery confirm. So that is why you select PayPal. If an item gets lost AFTER  it is delivered, buyer is responsible, HOWEVER, it you paid with paypal, the SELLER has to be able to PROVE delivery...WELL KINDA SORTA.

PAYPAL only Pays you back IF the seller has any funds at PAYPAL.

So..pay by credit card under PayPal.

Then if the item is never delivered, you can get a refund form your credit card company. 

If the item is not as described, either get a partial paypal refund, if you can, or send the item back with delivery confirm and get a refund form the credit card.

You can ONLY get so many refunds via Paypal and there are deadlines, etc.

You can use the threat of Paypal but what might occur is Paypal closes the account (puts a hold) and you get squat..unless you used a credit card under PayPal.

I have done thousands of great trades on Ebay. Good luck.