Does how much you spend on a rifle influence how much you spend on the optic, and do you find the ration changes as the cost of the rifle goes up?
No influence at all. I buy a rifle for a purpose or set of purposes and I scope it appropriately for those purposes. In my case my most expensive rifle is my lightest rifle. I'm not hamstringing it with a 2 pound or heavier scope. It has a nice 12 ounce Leupold 2.5-8X in Talley 1 piece aluminum mounts. I'm spending my money for portability. The accuracy is way better than I can use regardless of gun weight in the area I hunt.
Seems like my applications call for $400 - $800 scopes no matter what the rifle is.
Tom