Of course any chip that is recently recarved would lose all value, imo.

However if the recarving is done 100 years ago, that's a different matter.

Why wouldn't someone else see that they can turn a $20-$40 chip into a $300 chip, start working in their shop?

There is a guy that is selling ivory on ebay who clearly states that he carved (stimpled) the chip. He has been getting $200 to $300.

The answer to your question is: whether a recarve or newly carved, if done well people will pay $300.

Actually I'm thinking of having the guy do a chip with a picture of my wife one it. I assume I'll have to pay $250 to $300.