Kidding aside, I don't see how any "rule of thumb" can be useful, especially in a general sense. Everyone's idea of a "good" scope or a "good" rifle is different. From my perspective, the only way I will spend more than maybe 1200-1500 on a rifle is if it is for serious hunting purposes, and for a rifle like that I will only put on what I consider a "good" scope, i.e. a Leupold. That's my comfort level in optics...I know that S&B or Nightforce offer superior optics, but my vision doesn't allow me to utilize them properly and my wallet doesn't allow me to justify them. I would also put a "good" scope on a gun that I use a great deal, like some of my favourite .22's. I have plenty of rimfires that wear scopes costing 2 or 3 times the cost of the rifle, but we're still not talking about tons of money.
One thing to consider: I look at things like binoculars differently. They are observation instruments, used for long periods of time and to distinguish minute detail. For stuff like that, I won't scrimp. I have a Zeiss and a Swarovski, and feel the money is well spent. But riflescopes are for aiming, not observing. As long as optical quality is decent, I am more concerned with waterproofness, durability, zero-holding, general ruggedness and warranty service.
One thing to consider: I look at things like binoculars differently. They are observation instruments, used for long periods of time and to distinguish minute detail. For stuff like that, I won't scrimp. I have a Zeiss and a Swarovski, and feel the money is well spent. But riflescopes are for aiming, not observing. As long as optical quality is decent, I am more concerned with waterproofness, durability, zero-holding, general ruggedness and warranty service.
