I've bought both new and used reels on eBay and have had no problems.  I've bought only from sellers with 99% good ratings.  That, IMHO, is key.  There are so many ways to get a good rating on eBay that anyone who has less than that is suspect.

 

Also, with used reels, look the photos over very carefully.  You can usually tell whether a reel has been abused by a close-up photo.

Ive bought a Zillion and 3 Tatulas brand new with no issues.

The only thing I would look out for on ebay is the guys that buy reels to flip them. Most times these reels have little to no test time on the water and can have some issues most being minor. It still comes down to the seller, and their history.

I'm lucky to live in an area with an amazing local shop (Hook UP) and try to support my local shops when I can.  They do so much volume they occasionally have sales which puts products like reels at price points very similar to what can be found on ebay.

That being said a lot of the time its hard to not buy form ebay.  Saving 30-40 dollars on average is a ton of extra fishing gear you can buy.

 

Buying on ebay is no different than buying from a store.  AFAIC you have the same chance of buying a 'lemon' from either.  Just look at the feedback.  If they have a lot and its positive you're g2g.  Paypal has excellent buyer protection as well.