I replaced my Jeep Commander's ecu 3 years ago after receiving a warning about the transmission fluid running too hot... the reality was the temps were normal. It was simple: 4 bolts, 4 plugs, wait an hour or so and done. And it was ~ 200$. I'll try to find the site for the supplier and update this post. Oh, And the new one come complete with all of my Jeep's ecu updates up until that point... so worth it for the updates alone vs what the dealership quoted.
(The dealership wanted to charge me over 1000$ to just reflash the old one. Cant imagine their charge for a new one.
As it turned out the old one was faulty, so the refresh probably would have been a waste. Dealerships suck it so bad!)
Update: the label on the ecu has faded, so I'm not sure from where I sourced it. I do remember it was located in Miami. Google shows a ton of ecu rebuilders, however, so where I got mine isn't really that important.