This is a fear I've witnessed in my consulting process. That’s why it’s important to have a professional handling it. Professional benefit and fundraising auctioneers know how to respond if no one offers to donate the initial amount without it influencing other donors, but on the other hand they also know how to prepare so that doesn’t happen in the first place!
I always advise my clients to identify at least one sponsor at the highest amount you’d like donated. This has been anywhere from $500 to $1,000,000 in the fund-a-needs I’ve done. If you know of an attendee that will be coming that is planning to donate $10,000 to your organization, ask that they donate it specifically at the fund-a-need. If you have those one or two donors at the higher levels, it will inspire other people in the audience to bid at that level and the levels below. This will help to build momentum so you can capture as many $100, $50 and even $25 donations from the people who initially felt they couldn’t afford to give anything.
Generosity is so contagious! We just need to get the ball rolling!