M82's are entirely USELESS in airsoft. You'll get the same range and accuracy out of them as a rifle half it's length, a quarter of it's weight, and a sixth of it's price. The real steel version is designed specifically as an anti-MATERIAL rifle.
Why carry around a 40lb sniper rifle when a 12lb sniper rifle with kill the guy just as dead?
Anyway its around 400$ for a good TM VSR starting platform. From there you need a 120$ inner barrel and 35$ firefly hopup in order to be accurate and consistent at 300fps
From there you can go up to 400fps for a while
Once you want to go above 400fps you need 150$ for new sears. And if you want to make the rifle REALLY consistent you'll have to fork out another 350$ for a cylinder set
So your looking at around 1100$ to have a pro sniper rifle, plus mags, bipod, scope, etc
And FYI, most stock AEG's can't shoot worth crap in comparison to a fully upgraded AEG
This is airsoft, you get what you pay for. A $400 stock VSR will perform like a $500 stock CA M4. An 1100$ VSR will outperform a 1000$ fully upgraded CA M4.
A gun is a gun, a chinese AEG is crap, and performance is entirely based on quality internals