Here's one for $9k.
Ebay 2003 Cobra Engine
You're going to find that the 03 Cobra engines are going to be hard to come by. Seriously, why don't you just have a supercharger added to your ride. Have it tuned by a reputable shop, and make sure you don't lean it out so you don't lose any cylinders. It's not hard to get 400-450rwhp from an 01 Cobra engine. Keeping the TR-3650 and IRS together, now that's a different story.
Bottom line. Don't expect to find an 03 Cobra engine, complete, for less than what you can add a Novi 1000 or similar to yours.