If you print posters or postcards or flyers to advertise your auction, you probably already print the URL for your SchoolAuction.net website on them. Consider also printing a QR (Quick Response) code on the print piece as well - these allow smartphone users to scan the code (using an app like QReader or Google Goggles), which then opens their browser and takes them straight to the webpage you want to deliver them to.
Which page should that be? The answer depends on the goal of your print piece - if you are trying to stimulate ticket sales, send them directly to the Registration page on your SchoolAuction.net site. If you are advertising an online auction, send them to the online-auction Browse page. You get the idea.
There is an easy-to-use, free QR code generator at http://goqr.me - try it out and see how it works for you.
Roger