The official Apple way to repair when the power switch fails is to replace the rear cover. The power switch is integrated into the case and isn't available as an Apple supplied spare part. The rear cover as Apple call the case, is available to Apple Stores and AASP's as long the the iMac isn't vintage. Who ever looked at the OP's iMac wasn't much of a specialist.
If it was my iMac I would simply fit a momentary make push button switch adjacent to the old one, cut the old switch's 2 wires and solder to the replacement, simple. I've never had a power switch fail in the white cased or later aluminium iMac's, and only 4 in the 21.5" and 27" models since their introduction, not a common problem. When they do fail, pushing the button doesn't feel right, or the button doesn't move in. It's easy to check by attempting to power on by shorting out the 2 pins on the back of the logic board socket the switch connects to with the tip of a small screwdriver.
I doubt the OP will be back, trolls rarely do. I'm only posting this in case anyone else ever has a switch problem.