i would always be cautious when someone sells a car that needs "minor" work. i mean if the guy has the TPS sensor, why not install it himself?

in reality this is how I would look at it.

windshield 150
knock sensor? i dont know the price of them, but how does the guy know he needs a new one? sounds fishy, like the engine is already knocking/detonating
valve adjustments are typically 2 hours worth of labor at a shop, so pick your labor rate
rear motor mount? how did it break in the first place? sounds like this car was beat up pretty bad. depends on the mount but i'll throw the number 150 out there, but rear mounts are a pain to get to, especially on h22 swaps. if the guy doesnt want to swap a TPS sensor, i can see why he didnt change the rear motor mount.