I haven't, but I've been tempted. I have one company that is constantly asking for quotes, and they rarely take me up on the bids. I often wonder if they are using me for a pricing gauge. One thing I have added to my paperwork is a statement that says, "This price is only valid for 30 days from submission date." If they come back 2 months later, they're getting a new number.
It is a good way to get customers "skin in the game". Most people just pad the quote to cover the BS.