When I do sell my BRZ I won't be putting it back to stock. I haven't kept the original parts anyway, but to be honest I buy a car and use it for my daily commute so I'm getting maximum value from it. I don't expect to yield much value at the end and I never expect to recoup the cost of the mods. That isn't the point, I've already enjoyed their value.
It won't be for 3-4 years yet, when I retire.