I built my G&P from parts. I got the gearbox, receiver, and barrel which came to about £200. I spent about £200 on new gears, motor, piston, cylinder head and gate titan and another £100 on an optic, rail, grip and stock. It's been r hopped and has almost instant trigger response with precocking. I love it and it's mine but honestly it's not cheaper than getting a base gun to upgrade and customize.