In your EBAY ad, you might want to reword a thing or two IMHO.
Things like:
(though it is not registered and will need to be before it can be driven on California streets) - My question, why isn't it registered? The new owner will have to pay all past years that it hasn't been updated. (at least in Oklahoma) Something to consider.
Then:
If you bid and do not pay, we will have you sued for the full auction amount and all legal fees. If a minor bids and does not pay, we will sue their parents and/or guardians for the auction amount and all laeal fees. - To me, that sends a wrong message of if you sneeze wrong, I will sue you. Sue happy are we? I'm just saying. It's not very inviting but yet could be a battle to the courts. I know your intentions, but the approach is a little harsh to try and get the biggest audience to make a good sell.
Think of your auction as a used car lot commercial. You don't hear used car lot commercials say, come on in and buy this car or I will sue your ass off. Again, IMHO.