The parts and peripherals are worth $200, maybe $250. The frame has to be replaced. It would be a nice donor pistol for one of the Timberwolf frames from Lone Wolf.
To get back on task; Night sights, $.50 trigger job (look on Youtube), a case of ammo down range. Not much else necessary.
My G-20C EDC/duty gun. Ameriglo sights, $.50 trigger job, +2 extensions, 2 more mags (for a total of 5), a butt load of Lone Wolf conversion barrels. Oh, and a Streamlight TLR-1 light.