I was always leery of eBay as well....had a friend that bought everything through them and highly recommended it for buying......so, I opened an account a few years ago and man have I made up for lost time...... I've got good deals on everything from beard oil to truck tires to headlight brackets.
I buy as much, or probably more, through ebay as I do Amazon .... especially since Amazon recently raised their minimum purchase price for free shipping to $50 (trying to push Prime memberships) and most things on ebay ship free if you shop around.
The number one thing to look at is seller ratings....eBay is very serious about seller ratings.
I've only had one problem and it was an odd "no fault on the part of the seller or buyer" thing....the USPS delivered it to the wrong address and whomever got it in the mail by mistake either kept it or threw it away. Since the tracking info showed a "delivered" status, it was basically going on my word that I didn't receive it. When I sent in a customer service inquiry, ebay issued a courtesy refund out of their pocket, even though it wasn't really their issue.
I've used PayPal for a while and it makes life easier when ordering...no need to type all your info into different websites to complete orders...but, like Rastus, I have decided to dump them after recent actions taken by them that cost promised jobs.