TC3 can be either electric or nitro. TC4 is electric only, if I'm not mistaken.

Without more detail on condition, we would be guessing, Red. I have been offering a complete, functional RS4 Evo3 for $165 with spare parts and it's still not sold.

TC3 is a nicer car, so if it has a RTR radio, but needs a servo and PS, maybe $125?
R40's are $$$$ kits. If it's in good shape, and has a good engine, maybe $300...but those are my guesses.

Give better info and you'll get better estimates.