I don't remember the model #, but it's identical to my Bushmaster XM15E2S.
Only difference is that it felt lighter, and had the 1-7 barrel twist. Barrel was marked CMP 1-7 5.56 NATO.
I assume it's lighter weight is from a thinner barrel.
I saw one at a gunshow last weekend for $965 or $995.

Yesterday, my local dealer had a used trade-in for sale at $899.
I opened it up to inspect, and it was obviously never fired.
The hammer and buffer didn't have a mark on them.
The gun looked like it just came out of the box.
I talked him down to $835, and put a deposit on it.

How did I do ???

I know this gun is nothing special, but COLT's seem to hold their value pretty well.

This is my 1st COLT, and I've heard many good things about them, so, I figured I'd give them a try.
Hopefully, it performs as well as my Bushmaster. I'm VERY happy with it's reliability.

From strictly "how much should I pay for a Colt" standpoint, I think that you did very well.  I priced a HBar "Match Target" Flat Top at $829 about five years ago.  I think that prices may have dropped for the other brands, not sure about Colt.  

The important thing is, how does that thing function?  :)  

I suspect it'll do you fine.  Congratulations.  I don't think that you got gouged.