You may want to try posting a "want to buy" ad. Look in the red column at left of the TractorHouse page. 3rd item down. You have to register with them to let them know you're not a spammer. Enter model, part number, and a brief description of said part, and leave contact info/phone number. I've found there are numerous salvage dealers that work through this, that do not make listings, like in the page I sent the link to above.
I gotten calls in as little as an hour after posting, and as long as 36-48 hours later. I've also found it best to wait the 36-48 hours, as you may get several calls. Prices have varied, and mostly, shipping can be a lot more if it needs to be shipped a long distance. They will give you a price, and most should be able to give you a ballpark price on shipping. And I believe the seller has to give a satisfaction guarantee on parts.
Just for giggles, you may want to do a search on Google with the part number, or even ebay. I bought more than several parts for the old Case 310B from ebay. Guys that strip down 2-3 tractors a year and part them out use this method.
