Those are probably the Century G3 clone. I have one and it is very nice, but not $850 nice closer to $500 nice. They are ok but if you are looking to spend that kind of jack you should look for a SAR 8 Springfield made in Greece. I picked up one for just a little more than $850 a couple of months ago. There is also the PARS import made in Portugal although they seem to run a little more. These are as close to a German made HK that you can get without the HK mark.
The 308 ammo is fairly cheap and is fun as all get out to shoot. Just a note, if you are a reloader or like to save your brass the HK91 style is not the gun for you. Brass get striped, dinged and thrown far, far away.
The ones I have shot are very accurate.
Century quality is kind of hit or miss so,you would probably be better off with an M1A, they can be found for just over $900 on the Auction sites. A good FAL is another good pick as the mags cost a lot less, just not quite as accurate in my experience.