GunThings will substitute parts, such as a new barrel, if you want to pay the price difference. They have lots of parts and do refinishing as well. GunThings has a good reputation on the FAL Files.
And, from posts on the FAL Files people seem to be happy with the DSA G1 kits. DSA includes some new Steyr parts with their kit, and they also offer new barrels and refinishing as options. The DSA link: