There is a good chance the shops with higher prices might be higher priced models like the MOE Magpul models. The base model is just that with no flash hider on the end of the barrel either. They go all the way up to the Performance Center semi-custom model with its 18" threaded match barrel, Vltor stock and Hogue grip, which lists for $769 but can be had from a good shop for around $625. I am pretty sure the one you have it the Standard model that lits for $499.
If you want to lighten the trigger I suggest going online to Brownells and buying the JP reduced power spring set. That will get the pull down to the 3-4# range.