Be careful when buying coins/medals online - an anecdote
I recently recalled an interesting experience happened one or two years ago. I found a City of London medal on the website of some auction house. Normally a city of london serie medal is very expensive: $400+, rencently 600+. The starting bid of this piece was something like $80. The auction house was very professional and stated "The back of the medal is cleaned" in the description even though it was really hard to see that even in the high-res photos. I don't like cleaned medals so I didn't bid.
The interesting part is that after about a month, I saw the exact same medal on eBay, with all the description directly copied from the the auction house, and guess what, except the line "medal is cleaned". It was listed many times more expensive then the hammered price and was bought by someone days later.
I have been particularly careful when buying things on eBay since then LOL.