The solenoid for a T7 is not that expensive! Here in Sweden, it´s about $50! The T5 solenoid on the other hand is verrry expensive, like the price you´ve got.
Hitting fuel cut off is not good for the car, don´t do that often!
Disconnecting the APC (solenoid) is good way to test that the WG is working correctly. With the valve disconnected you should see a little boost, but not more than a little bit into the yellow area on the stock gauge. If you get more than that, your WG may have problems.