Key, ignition ring, skreem, gauge cluster and dash, all coded together, if one doesn't work, it will tell the computer not to start the car.
Hopefully someone can chime in and would know a general price range.
But sounds like there is another problem besides the original ecu.
You say no start, you mean cranking and not starting or not cranking?
if it is cranking but not starting, has it ever shown sign it wanted to start?