A quick search at Devot-ee shows no auction add-ons, though it's possible that one was created and not posted there. But, I do recall their being a discussion about an Auction Module for EE awhile back and went searching in my bookmarks.
The reference I found was a tutorial on how to build your first module, an Auction Module. The tutorial is done by Andrew Weaver, who's built a number of great add-ons for ExpressionEngine. It's part of his ExpressionEngine Add-on Recipes website, which is…
a collection of articles and tutorials to help you learn how to build
So far there is an eight part series on 'Building an Auction Module'-Our First Module, that can probably be stepped through in under a week. Downside, you'd need to do it yourself and I'm not certain if the series is fully complete or is at something like 8 of 10 entries. But Andrew could probably be contacted to help you finish off any remaining components. His email is available right on the site.
I'd think that after the auction is won, you could probably use Simple Commerce or Exp:resso Store to handle the final payment transaction. That part could be a little tricky, but shouldn't be to hard. All auction items would need to start with a base price/bid, that will allow you to complete the Store record. But the final price could possibly be handled the same way donations are, by using the quantity field instead of the price field, when the price field is set to $1. That way a bid of $500 would be Qty: 500 x Price $1, to record the final sale price.