potvinzcat
I'm your Private Signer, Verified Trader,
if i was selling this card what would be my asking price and what should i not sell it for less then
do some research on Ebay. See what some of the white hot cards are going for and see if you can find somebody similar to the Guentzel if there's not one already.
put a price in the same neighborhood and enable Best Offer. See what offers you get and settle on something that you're happy with. Best offer also enables you to weed out the people you don't want to sell to. For example, low feedback, weird feedback in their history, etc.