What kind of long range are we talking about?
A lot of what you’re paying for in a more expensive scope is the warranty and the optical coatings that help you see the target better in low light conditions. If you’re not shooting in low light conditions and can baby your equipment maybe you can get by okay with the less expensive stuff.
The more expensive scope makers manufacture their own glass, so quality control is definitely better. The only optics I own are from Burris & Nikon and I’ve been happy with both. Vortex Optics seem to be one of the better bang for the buck optics, from what I’ve read but have no personal experience. Depending on the rifle you’re using it with and amount of recoil, the cheaper scopes may not hold up too well over time.
http://forum.accurateshooter.com/threads/this-is-the-best-scope-for-the-money.3918265/
I’m hoping to become proficient out to 1,000 yards with a Remmington 700, .308.
The Monstrum scope I’m looking at has a 1 year warranty, and claims to be able to handle that platform.
What parts of the optics are susceptible to wear and tear on a .308? The standard ammo looks to be 150 g.