Computer Replacement 2001 E38

Hi Guys;
I'm in need of some advice. I have a 2001 740il with 125K miles. The failsafe engine/transmission warning, non functioning tach, ABS light all happened at once. Had the car towed to the repair shop (non-dealer). I was told today that the thermostat failed, overheated wires going to the throttle body causing a short and thereby destroying the computer. What I'm looking at is replacement of the computer ($1500), throttle body ($500) and thermostat ($200). Has anybody ever heard of this happening and is this even plausible? The mechanic says in 25 years of working on BMWs he has never seen such an occurrence. Any ideas on the purchase of a used computer? Thanks in advance for all suggestions.

Rob.

You can get a computer for less thats bmw retail : http://www.rmsonlinestore.com/main.sc also trottle bodys on ebay or even here there are used Dinan for less and Pelican and oembimmer parts have better prices for thermostats