I got mine from ATK - 2000 and paid a mechanic 1000 to put it in - this included replacing the water pump, tstat, new plugs, hoses, oil sending unit, and had the trans fluid changed.
Put 1000 miles on it and just changed the oil. She purrs like a kitten. So, for 3000, I got basically a new vehicle. Not a spot of rust on it and it shifts smooth. Getting 16 mpg, a drastic increase from before.
Note that the 2000 was actually 2500 - they refund you the core when they get it back. Tax free and free shipping.
I'm glad I went the crate route. I looked high and low for a jy engine, but the cheapest I came across was 1500. For another 500 I got a brand new (reman) engine.
The 4.0 is fairly easy to swap out. I probably could've done it myself, but living in a townhouse, my space was limited. Well worth the expense.