A few tips for folks who want to speed through the line for item drop-off and cash out:
1. Have your con badge mailed to you so you can skip the line at will-call on Wed. You will not be allowed to drop off your items without a valid badge for this years con.
2. Consider using an auction 'waiver'. Normally, you wait in line and a friendly auction volunteer will check in your items one by one to make sure that you have everything set up correctly, (correct tags on each item, not putting a 1st edition DM guide in the shop for $5). If you are confident that you have entered everything correctly during preregistration, you can simply sign a waiver and drop off your items. NO WAITING IN LINE.
3. Request a partial payout. Usually beginning on Friday, you can request a partial payout of what you are do on items you have already sold. If you are anything like me you will then promptly turn around and spend that money right back at the auction, but if you are a party pooper, you can take the money and run as well. You can mostly "cash out" on Saturday and then just wait for a small check in the mail a few weeks later.
4. Consider abandoning your unsold items for a good cause. If you don't want to wait to get your unsold items, just leave them. Any unsold items will be taken care of for a year and return to the following GenCon as items in the charity auction.
Source: I am an auction volunteer