Replacing people with robots sounds more costly and counterproductive. Plus, where will all these people work then? Robot labor is not something we should be encourage nor welcome as it just means more homelessness and poverty.
Some people would certainly go for cybernetic enhancements for the sake of having them, but as you said it would be expensive and I doubt many people would be up for it, but they'll still be there. No point in trying to stop them, it's not like they'll be killing themselves.
If I needed robot parts, I would get them. Otherwise no dice.