JBD,
Stag is a great brand to go with. They are basically made by Continental Machine & Tool (ie- CMT), who have been in the firearms biz for a long time. CMT makes quite a few parts for most of the other manufacturers of AR's out there, so they know what they are doing.
The Stag Model 1 is one of their entry level models, but is still a great way to get into AR's. And the best thing about the AR platform, it is very easy to upgrade and modify to what you want it to look and perform like, just by switching out parts.
If you can get that one for $800 to $850 that isn't too bad. There is a site that I will link here, where I recommended Tango to look for his Rock River. The name of the site is AR15Sales.com (aka - Legal Transfers, LLC). Here's their link:
ar15sales.com
If you notice on that page, he lists a Model 1 complete upper assembly for $504 - complete with the bolt carrier assembly and bolt.
The reason I point that out is...if you scroll to the bottom of the that page, you see an "Add a Rifle Kit" for $140 - that has all the parts to build a complete lower assembly - EXCEPT for the lower receiver.
If you are following along, the two would cost = $644.
Now...you can do this a few different ways. IF you are willing to LEARN more about your AR, you can do so, by ASSEMBLING your own lower receiver. YES...you can do it.

Quite a few of the folks on here already have, and are a great source of info and encouragement.
So, if you go to this link:
Dynamic Armament
you can buy a COMPLETE Stag lower receiver assembly for $275. Now, the lower receiver is the ONLY part of the AR that is registered. So you would have to buy it through a dealer or FFL. Unless you can find a complete lower assembly in your area, you'll most likely have to pay a Transfer Fee to have that assembly sent to your dealer, where you can pick it up.
If you buy the lower assembly separate from the upper assembly, it normally saves you a few bucks in taxes and fees, too.
OR...you could buy the first two items I showed, from AR15Sales, then buy a stripped lower receiver. The rifle kit above has all the parts you'll need to put your stripped lower together.
Again, from Dynamic Armament,
Dyamic Armament - Stag receiver you can buy a STAG lower receiver, stripped, for $99.99.
Okay...let's do the math. The first way, buy the upper, the rifle kit, and the stripped lower.
Upper = $504
Rifle Kit = $140
Lower = $100
Transfer=
$50 (I purposely went high there, depends on your dealer)
= $794 
WOOOHOOO !!!
Now...let's look at the second way...
Upper = $504
Lower assy = $275
Transfer =
$50 (I purposely went high there, depends on your dealer)
=
$829 Again...not too bad.
So either way, you'll come in UNDER $850, and have a complete STAG Model 1. If you look at the AR15Sales site, he lists all the other model upper assemblies, too. So by picking one of the others, you can put together any model of Stag you want, and know how much it would cost you.
Just a few ideas for you. Pete, at AR15Sales.com, is an excellent guy to do business with, ask Tango. He isn't the most warm/friendly person in the world, but is very knowledgeable, and provides excellent service, too.
Anyway, good luck, and welcome to the world of SUR's.
Slo