Ore busters: ~95k-115k Diamond supporter vouchers: ~130k-150k Keep in mind that ore busters are constantly rising in price too.
Ore busters are worth a good amount less than diamond vouchers as nick said, but if both parties are in need of said items the trade could still work.
An ore buster? Depends on how many you have. I'm guessing it is worth if you have more than one ore buster.