I sometimes buy things on ebay, always went fine. Find item on ebay, pay with paypal, done.
Lately though there is this new trend where large sellers use a sort of third party to manage their sales, like e.g. channeladvisor.com. Not only does this add an extra step to buying it also adds an extra step that can go wrong.
On one auction I get mails from channeladvisor to pay for an item I already payed via paypal, yet didn't receive.
On another auction I was sent along to a totally confusing german only third party site, causing me to accidentally pick the wrong payment method, which turns out I can't use, and I can't change it, thus I can't pay.
Don't bother to send a message to the seller, because for them you're just collateral damage. One negative feedback on thousands of sales.
I won't be buying from indirect sellers on ebay anymore...