Subaru Loyale Throttle Position Sensor

My mechanic has diagnosed a failing throttle position sensor on my 1992 Subaru Loyale 4WD (non-turbo). (First, he replaced the plugs and wires.) Neither he nor I can find a replacement for less than $250. That seems excessive—does anyone know if there’s a non-OEM version that’s cheaper, or whether one from another model would work? Is there an intemediate repair between wires/plugs and the TPS that I should try first?

Thanks for any advice…