I want to get my Rem. 1100 20" set-up for the rem-choke system, and I need a sight put on it.
Can anyone help?

What part of oregon are you in, caise I know of three, one in Rainier, one in Astoria and one in Tillamook.

It has been a few years since I have had any shotgun 'smithing done, but that doesn't change economics much. A (ethical) gunsmith is rarely going to be willing to do machine work on a barrel (from a current production gun) to duplicate what is currently available for purchase from the factory.
Remington offers a 21" barrel with the Remchoke system, direct from the factory. Their MSRP is $216, which means you could get it cheaper through a stocking Remmy dealer.
A gunsmith would be hard-pressed to do the machine work for this price AND touch-up the bluing too.