The Nametag shop is located in SanFierro near the police station. Here you can change your nametag color.

Just enter the colorcode you want to have.
You can enter values from 0 to 255.
It also has a roof acces. :D


Because the shop is slightly bugged you need to take more money with you than is actually required. The new Nametag costs 1250$ but you need to take like 5.000& with you.