From time to time I see US Mint dies for sale. Obviously they have the part that minted the coin ground off, but it's still cool looking and something that I want. However, there is really no known value for them as far as I know. What price would be acceptable to pay for a cancelled die?
The ones that are completely ground... are worth in the $25-$30 range. With the design left on them like the one below they are worth several hundred dollars. http://www.cointalk.com/t197921/
I have three that I have purchased for $15-$25 each. 2 are cent dies and one is a 2004 Texas quarter die. I just think It's cool to have one.