I usually donate a gift certificate also - I put in there that they get a custom designed and decorated cake for whatever occasion they have in mind. Total value of the cake not to exceed $250 (or whatever you are willing to make) - and then I made sure to put on there that they must call at least 3 weeks prior to the event to place the order.

If they pick a cake that goes over your value you can just charge them the difference or tell them that that is not included in the certificate.

The last one I donated went for over $300 - I always put my book of cakes on the table for them to look at.

Good luck!!!

Thanks so much everyone for the awesome advice and for the search suggestion xstitcher!

All these are great ideas. Thanks so much, as I have a silent auction coming up in October and was wondering what I should do as well. I'm also making the dessert (mini cupcakes) for the dinner at the auction and was planning on multiple flavors and combos.