ECM / Computer Replacement

I started having a problem where my GEN1 1999 Avalon XLS was taking 2-3 retries before it would start. The car was turning over quite strong but wouldn't start. Seemingly out of luck it would start around the 3rd or 4th try.

Since this didn't seem like any a battery problem I took it to the mechanic. The mechanic suspected it was a transponder key problem and so he called me back to bring my other set of keys, which I did. When I got there the vehicle wouldn't start with the other key either. The way it was turning over though without starting it did remind me of how the car behaved on a non transponder before I realized I had to buy and program the transponder key when I first bought it a few years ago.

That mechanic didn't get very far with it, but he passed my vehicle along to another mechanic friend of his that was more familiar with electrical problems, who diagnosed this as a computer problem that needed to go to the dealer. I asked this guy if he'd be willing to fix the problem if I bought a computer from the junkyard and we called an auto locksmith to clear the computer and program the keys. He refused. Neither of these guys charged me luckily since they couldn't solve the problem.

I called the dealer to check to see how much they would charge to replace a computer and how much the part was. Their quote was 1-2 hrs of labor, and $1800! for the parts if the computer had to be replaced, but they did say that it was very rare that the computer had to be replaced. Since I have been taking my car to these smaller shops that maybe don't have all the know-how I suspect that the computer might have really been blown. This problem just popped up after the same mechanic above was unable to diagnose an AC relay that needed to be replaced (2nd time in 2 years).

Hesitant to go to the dealer and pay $1800 for their computer, I checked with a bigger shop down the street that said he could do it for $600. After leaving the car with him for diagnosis, his price jumped to $900 ($650 parts, $200 labor, $50 tax). I didn't have the time to deal with yet another tow, and my trusty mechanic, who is now growing very old, didn't want to do "this kind of work" either, so I left it with him even at $900. I did bicker with him telling him that we can find this computer for $75-$125 at the junkyard and can hire an auto locksmith to do the programming, but he said the place he was buying the $650 computer from was going to give him support on it and help clear/program it, plus he said he'd give me a 6 month warranty, which helped because I wasn't sure if there was another short/fuse that caused the computer to blow (I did tell him about the relay). I just found out today that he wasn't able to fix it, or get the support they promised him on the computer. He is now telling me to take this to the dealer.

Has anybody had any similar experience with their Avalon? I don't mind taking this to the dealer, and don't mind paying them but I am really hesitant to cough up $1800 for an ECM! If it's just labor it seems like it should be reasonable

It seems like I should be able to just find a junkyard with an ECM and a transponder key, and put the transponder key in the glovebox to keep the car starting. Has anybody else replaced the ECM without going through the dealer? Anybody done it themselves, or with the help of the auto locksmith?