OK, not sure if this is to high of a price. A guy I work with has a real nice 100% upper that dates between 1964 to 66  and the lower is a Nodak with semi auto FCG parts that are gray. The complete retro is a clone of the XM16 E1 603 model. I am thinking about buying it. He is asking $2000 for the rifle. Bolt is correct chrome not sure about the buffer. Your thoughts?

I had your problem. I decided to buy a sp1 for $1000 and was happy.

Value of a clone is usually the sum of the parts and more sentimental or should I say if you're happy with it that's all one could ask for.  If upper is early square forge,  BCG is true XM16E1 chrome,  buffer is an edgewater,  tube is early no wrench flats and barrel is correct it would be very hard to find the parts and build for those coins IMO today especially if condition is really 100%.

Key words  IF THEY ARE LEGIT ORIGINAL PARTS. some times its hard to tell. Id prolly do what first post says, get something else. Maybe, just maybe if it was all legit and complete and perfect.  But more likely no than yes.... At least for me.

I would suggest that you study the configurations shown in the link below and determine if that rifle does have the proper parts. As Cdenmark mentioned above,it's worth the sum of the individual parts. That said,then you would need to figure out just what each part is worth.That's the hard part as original early parts for the XM16E1 have not popped up for sale recently. Many of us can help place prices on the parts for you based on recent past sales or from completed auctions. BUT 1st you need to determine exactly what parts are on the rifle. Link below.Good luck.
http://www.retroblackrifle.com/ Click on "Military Rifles"

Before deciding if you want to buy it, post photos here.  As many as you can.  Show us the receiver on both sides, any markings on the barrel. Pull a handguard and show us the gas tube and the heatshields of the handguards.  Show us the buttpad and the buffer and the BCG parts and try to get shots of the internals.

The hive here will tell you what's original and what's rare and whether the rifle is worth the asking price.
A lot of people will leap to the "too much" conclusion, but if we're looking at 602 parts or XM16E1 parts, he might not be out of line.

+1  Follow the advice given in the 4 previous posts concerning said rifle, they covered everything between them.