One of my co-writers and I did that.
We auctioned the chance to have characters in our next book to be named after the high bidders.
Five people won and we raised a nice chunk of change for a major charity, not our own poor selves.
Earning enough money to live on while writing is why one keeps that pesky day job.
Believe me, I thought of doing such an auction to get some much needed gelt, but it left a bad taste in my mind.
By the time I'd finished the webpage it was to go on I imagined how my friends might react, factoring in just how little traffic actually comes to my website in a month. If you're a best selling writer you probably don't need the money, and if you're not, then you won't raise enough money to cover expenses.
The whole scheme would have been a terrible embarrassment. It's wonderful that readers shell out their hard earned money to just buy my books. I'm grateful. How could I ask them to send me more of their own hard-earned cash just because I use my WIP as an excuse not to get a job?
Once I deleted the page I felt better and the gods eventually favored me with a day job that I actually like.
I still auction stuff, but it ALWAYS goes to a charity.