Found eBay good for tools, glue sticks, fibreglass and resin. I have spent thousands and saved hundreds compared to local and mail order shops.
However, you need to treat eBay as just another online shop and not get carried away. I tend to stick to sellers with positive feedbacks in 4 figures at least, unless I am after something unusual/rare. Anything expensive or large I will only buy from someone within driving distance so that I can check it out before handing over the cash.
I won a pair of screen trims for the Elan, but then found that the guy didn't accept PayPal. I was unhappy to send a cheque as there was no safety net like that offered by PayPal or a credit card. So the guy said, after we had had a chat and discovered that we were both Elan nuts, that he would send them to me and if they were acceptable I could then send the cheque! Now, that is trust, I wouldn't have done it! They were perfect so the cheque was swiftly sent off.
If all eBayers were like him it would be perfect. Unfortunately, however, it reflects real life.