Like saramwrap said there are many factors that go into buying and selling on ebay. There are sellers that charge $8 for a 1/4 tsp of pigment plus shipping which is insane...But there are other sellers that charge $8 for 1/2 tsp which isnt so bad considering the going price for a 1/4 tsp is 3-4. A few of the sellers also include freebies, and not so horrendous shipping even for out of coutry. Ive bought and sold A Lot on ebay and Ive only had a few complaints in being overcharged and it was usually a shipping factor.
You cant really complain about ebay unless you're an avid user, seller and buyer. eBay is an enterprise within itself, and you Don't HAVE to use it. Its a nice resource when looking for vintage or discontinued items, or even htf rare items. At the same time there are sellers that know that people don't know enough about certain items and take advantage of that. For instance I was looking for the maxiglide hair system for my daughter. I know how to research so I did, I found it on amazon for $70, and on ebay starting at $90...So needless to say I knew not to bother with ebay for it.
Being an informed and knowledgable shopper is your burden, and honestly it will save you tons of money in the end.
I know I used to be a omg I want that bid away person, but now I realize that if I take my time and research I can usually find a good price.