The very rough painted solid green turns me off
It would me also - for that amount it should have a pretty nice figured walnut stock. Quite frankly it's one ugly rifle.
in that you reach a point where you have to pay MUCH more to get only small increases in performance and, even then, it may be hard to tell a difference. Is it worth it?
This^
There is no doubt there are some guns that are typically reported as being 'moderately' accurate or varying degrees of accuracy from one to another of the same gun. A good example of this is the Ruger Mini 14.
Then there are some guns that are relatively moderately priced and are consistently very accurate. Two examples would be CZ and Tikka rifles.
Consistency in a product's performance is a selling point regardless of price.
There are obviously accessories, add ons etc. for a lot of guns that will improve ones accuracy with a particular gun and there is no doubt the high priced 'custom' guns are probably built with a different level of 'attention' during manufacturer but that is not to say many popular name guns are built with any lessor degree of quality.
It is often stated 'The gun is more accurate than I am' and in most cases this is probably the truth.
I have always been satisfied with the quality production guns I own and have owned and have never felt the need to spend 3-4 times the amount for one I doubt I will shoot any better.