An author named Brenda Novak hosts an annual online auction to fund the search for a cure for diabetes. A lot of her author friends offer their books and other stuff for sell at the auction. There are a few who are offering manuscript critiques. The one that I think would be very valuable is the one offered by Kristin Nelson, national literary agent who specializes in women's and speculative fiction (but also does others). If you write in that area, you might want to keep an eye on her item.
I've never tracked this auction before, so I have no idea how high the bidding will get. But what an opportunity!