I don't know the inflation rate between the late '60s and now so I can't address the price comparison.
I do know a bit about the Vietnam Era Scopes. The Models 70s for the most part used the Unertial target scopes. The Marines and Army both looked at this system in trying to find a decated sniper rifle. Both decided that the target rifle would not hold up to the riggers of combat.
The army went with the ideal of putting a scope on an M14. (M21) The M-14 had already proved to be a reliable rifle in the jungles and rice paddies of SE Asia.
The Scope they chose was the ART Leatherwood. It was a heavy durable scope. (I have the MPC version and it still works today). The ideal is the rifle can be used with the scope or without.
Based on my experience going to sniper school and teaching sniper schools with the M14/ART is they do hold up, they do keep their zero when you take them off and put them back on.
The M14 used was a match version, meaning better barrel, 1/2 MOA sights (instead of the 1 MOA), opened up the flash suppressor with a #7 taper reamer to keep rain drops from gathering inside the suppressor interfering with the bullet.
The main advantage with the Match M14 was impregnated stock. Basicly the stock was put in an oven and all the moisture was removed. Then the pores of the wood was impregnated with a sort of glue that made the stock immune to moisture, which was a big problem in Vietnam.
The M21 also had the ability to be used as a battle rifle without the scope so the soldier didn't have to pack another rifle. The M21 could also be used with the Startlight scope.
The Marines with with the Rem 700 Varmint in 308 and the Japanese made Redfield Accurange Scope. Calling it the M-40. The Rifle was accurate enough but at first the stock had an oil finish, and unlike the M21 (Impregnated stock) was subject to the effects of moisture. Also the Accra range scope wasn't as positive with its range finding as the ART. With the redfield one had to get the range estimate, then adjust the elevation knob where as when you got your range with the ART, (Automatic Ranging Telescope) you automatically adjusted for elevation.
Most Marines would zero the rifle at 500 yards and hold over/under.
A few years ago the NRA American Rifle Mag had an article about the two systems, reporting the M40 spent more time in the maintainance shops then the M21.
Both services went to the Remington after the war. The marines up graded the M40 keeping the short action and no means for iron sights.
Several other combinations were tried in Vietnam, but these are the two that made the grade and came out of that conflict.
The Army adapted the Remington, called the M24. It was a long action so eventually it could be modified to accept the 300 WM Round. Also the Army kept the ability to use iron sights on the M24.
Both Services went to the Mil Dot system for range estimation, one version or other of the Leopold scope.
Now several high grad expensive (Nightforce etc) scopes. They work but I don't know how well in a jungle environment. Too many moving parts. Scopes now are also battery dependent. I've had bad luck with batteries in Arctic conditions and I'm not sure how they would hold up in several weeks exposed to extreme sub zero temps.
The more moving parts one has, the less "soldier proof" it is. Another concern I have with the new systems is weight.
A simple ridgid fixed 8-10 powder with Mil Dots would be hard to beat.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071