Bout 600 for the throttle body assembly, 400+ for the ECU, and lets not even talk about the $80 an hour a shop will charge to find out what the problem actually is. And its not uncommon for them to be wrong.
I spoke to a guy that spent 1 grand in labour and miscellaneous parts at a shop trying to find out why his KX450F wasn't getting fuel, turned out to be a whole new computer was needed, costing another $800. Theres hundreds of storys just like that. Know what I do when my bike stops getting fuel? Pull the carby apart and clean it. 2 hour job. Free.
As I have said previously: If the manufacturers are willing to offer a 10 year guarentee on their electronics that are not fair wear and tear parts, I will happily run out and buy a new EFI bike. But they won't. I have no objections to EFI whatsoever other than what happens when it stops running?