In fact there are a few companies specialised in testing / repairing ecu's (there about 2 or 3 in the United Kingdom, perhaps in the US ?)
Instead of buying a new one, Id' go for a used one, I don't even want to think of how much it would cost.
As for installing it, you can really easily do it yourself. It is located behind the glove box, you'll have to unplug it and plug the new one in, and that's it !
BTW are you really sure the problem is with the ecu ?