If you are hosting an onsite event, consider a Paddle Raise. Your MC or auctioneer asks guests, for example, "We need $10,000 to purchase [something], who will donate $1,000 to help our great cause?" Guests then raise their paddles high in the air, you write down their bidder numbers, enter them into your BidCoz software, and Wa-La! the donations are added to the user's checkout cart.
Donors submit payment right away, wait until the end of the event or, if a credit card is on file, you can click Auto Checkout.
A Paddle Raise is a great way to fund specific needs.