I would think that throttle setup is QUITE hard to find;
I have only ever come across the one.
I agree that the ebay seller of the throttle stop is way high - but these have never been cheap.
Back to the TCS solenoids, if they are selling at, or around $80usd (plus shipping) then the market is dictating the prices.
I am unaware of these ever (ok, since I got my car in the mid 1990's) being sold as replacement parts - just normally disconnected, or tossed all together.