Usually pretty expensive to have that done, lots of time on a machine unless someone has a CNC Lathe with a milling head as well, in which case it's not much time but a lot of cash per minute/hour of use.
Aside from looking cool, the dimpling only helps with heat dissipation - which with even 10 round mags and semi auto only - doesn't come into play too much.
However if you're willing to pay the cash for it, I'm sure someone will say yes to it.