For the 22-250, I will second the recommendation for the Minox ZA-5 4-20x50. It is a nice scope and fits the rifle well. For about $700, it is a good option.
For the 22WMR, the Pride Fowler is a good option if you want a holdover reticle. If you are OK with a simple reticle, there are many good options out there and I would be looking at a solid 3-9x40 scope, something along the lines of Zeiss Conquest or Minox ZA-3 3-9x40 or Meopta MeoPro. A scope like that will run you around $400.
For the 308, it gets a little more involved since you want something with good low light performance that can also double as a long range scope later. Since we are talking 308Win on an AR platform, I will assume that long range in this case means "within 800 yards". 308 can definitely be stretched further, but that is probably where it is at its best.
What this is telling me is that you want a combination of large objective lens, moderate magnification (you need a large exit pupil for low light) and easily adjustable and repeatable knobs for when you need to shoot a little further. The reticle also has to be conducive to both low light use and precision shooting. All of this has to fit into your remaining budget, which is about $1k (by the way, I hope the mounts are coming out of a different budget).
What you need here is something along the lines of a 3-15x50 or 4-16x50 or either of those two configurations with a 56mm objective.
This is a tough thing to find within your price range. Weaver Tactical 3-15x50 is a good option as is Vortex Viper PST 4-16x50. Weaver is a little better optically I think, but both are goo dfor the money and stay within your budget.
IOR Tactical 4-14x50 would be a good option, but it is a little outside your stated budget.
Generally, this last scope should generally be more expensive. Or, if you delete the long range requirement, there are several good quality 2.5-10x56 and 3-12x56 scopes in your price range with 2.5-10x56 Trijicon and 3-12x56 Meopta Meostar being my favourites.