Those prices sound about right. Buy online, not in stores. Where in Texas are you? It's a big state... I'm in D/FW.
I guess you're asking for opinions of the parts you have selected.
Superior Arms makes great stuff. [check]
Rock River Arms makes great stuff. [check]
YHM makes excellent stuff. [check]
Bushmaster makes excellent stuff. [check]
SOG Vertical Foregrip (VFG.) I dunno...
Buy mags from 44mag.com. Get the ones with Magpul followers. I think they're like $12 or something.
Now, the big question is what kind of barrel are you getting? Is the R4 barrel truly an M4 profile, or is it heavy under the handguards like a HBAR? Is it chrome-lined? I would reconsider if its non-chrome-lined and heavy profile.
I have ONE flattop rifle with a detachable carry handle, but that's because it's my "M4 Clone" model. I wanted a rifle that was basically identical to a Colt LE6920 in my collection of US service rifles. I have an M16A2 clone as well. I'm still deciding whether I want an M16 or M16A1 clone.
Other than that, all my other flattops have BUIS (Back Up Iron Sights) and optics (Eotech, scope, etc...)
If you are going to "use" this rifle, get a BUIS for use with an optic in the future. It gives you more versatility. Of course, if you want a carry handle just for kicks, go for it, but don't pay more than the $75 on that link.
Welcome to the board. Shoot me an email if you live in D/FW and want to learn who sells what around here.