As an archaeologist, I get itchy when I see any original finds on sale anywhere. Itchy, and sometimes also a little bit angry, and always a good bit sad. Removing finds, taking them out of the soil, destroys irrevocally some knowledge that we could have gained about an area, a find spot, a development. This can be true even if they were stray finds that turn up on top of a field that had been ploughed.

Selling original artefacts supports the market for original artefacts. It does not matter where they come from, and it does not matter whether they are expensive or cheap, stray finds or not - everyone that buys or sells artefacts strengthens the market, and the stronger the market is, the more attention it gets, the more treasure hunters will go and try to find (and sell) stuff.

This destroys archaeological sites. It can even destroy more - such as this Roman bridge in Bulgaria that collapsed due to treasure hunters trying to find a gold treasure supposedly buried at or near the bridge.

I am out of words about this. Our world is one Roman bridge poorer because some people know no boundaries in their greed for treasure. Sometimes, I have a hard time to believe in humanity.