Depends on your comfort level working on your own vehicles. One of the big things these need is electronic diagnosis so you need to be more than just a little familiar with a multi-meter.
If you're fine with that then GovPlanet is probably your least expensive, as far as immediate out of pocket cash. Be prepared for some major expenditures right out of the gate though as there's no telling what is left out of the auction descriptions and what will break the minute you get it off post.
You can spend a little more and either find one in the classifieds here, check with other owners for leads on ones for sale, or spend a LOT more gambling on the public online auction sites.
I got mine through GovPlanet but wound up putting about $1000 into it before it was drivable. Still that was miles cheaper than getting one off eBay.