Being an eBay maniac with over 1000 feedback's, one of the best ways to get a smokin' deal on eBay is to buy more than you need and part the rest out.
My personal favorite was when I bought 2 1932 Ford pickup doors for $300 a piece because the seller didn't off shipping. Marcsrollin and I drove up there to pick them up, I think it took us 6 hours or so each way. I took the parts off the doors that I needed, striped and pieced out each door, put each individual part on eBay and offered shipping, and I got about $1,000 for the parts AND got to keep the parts I wanted for my project. I don't think it would be realistic to expect that kind of result for a jet pump and place diverter combo, but it would have been possible to pick that diverter and pieced out the rest to make up most of the difference.
Another great way to pick up parts cheap on eBay is by winning bids on parts that are miss spelled. I got almost the entire front suspension for my '32 by being the winning bidder on a "hot rod front suspention" with no pic in the listing. Whomever saw it probably didn't bid on it because it didn't have a pic. I recieved a '33 front axle, a pair of split wishbones, front spring, '48 juice brakes, and all of the appropriate hangers. I probably saved $500 easy on that one. I've got less than $1,500 in my '32 and I have all of the major parts for it.