G17.
I spent a lot of time lurking around GlockTalk and some other forums and it seems the G17 offers certain advantages to building a plastic go-fast-omatic...not the least of which is low sticker shock. I just bought one from Gunnar for $650+
Trigger/action work looks pretty simple - and relatively cheap.
I picked up a barrel and comp off the EE and now I am looking at optics.
Seriously considering the C-More STS with a dovetail mount.
The key for me is to be able to do as much of the work as I can or buy 'drop-in' parts to help keep the cost down. The hard part is trying to be frugal but still keep quality in mind.
I am not worried about being the next world champ I just want to have fun....
John