well it could also be the wiring from the engine to the ECU. did the toyota casa do an ECU swap to determine if your ECU is busted? if they did, then ECU nga.. because it's possible an important sensor (e.g. crank sensor) is busted, this will *look* like a busted ECU because the engine won't run at all.

standard practice naman daw ng casa to do an ECU swap when there are weird non-mechanical problems. This rules out the ECU right away.

75k for an ECU is highway robbery. You can probably get it surplus, call Nankai in Banawe 7477827.