HOWEVER, if the used gun is old enough that it has the metal trigger and guiderod, AND is in comparable shape as the new one, I would get the used one. The plastic trigger and guiderod bugged me and I spent $90 to replace them on my M9.
I'm curious as to why it cost so much to get them replaced? I'm assuming that's gunsmithing fees. A new metal trigger and metal guide rod are around $40-$45 at most for the parts and only takes 15 minutes to replace. I've changed out tons of these before.