Answer: I'm glad you are seeking advice and direction. You've done a lot of work already, and you want to make sure your efforts are worthwhile. I suggest that you consult with a Forest Service Forester (you'll find the Forest Service listed in the phone book) or other professional before you go further. They'll be able to tell you if money is available for your efforts.
A couple of notes: think about the longevity and growth habits of the tree species you're working with. Will the full grown trees you propose to transplant be able to reproduce young trees to take their place? Hopefully they will, especially since aspen are relatively short-lived anyway. You don't want to have to replace your full-grown trees in 15 years with another forest-full of full-grown aspens. They should have offspring or sports to take their place.
Sagebrush is growing because the environmental conditions favor it. It's a signal of a marginal environment that won't support other vegetation, such as lush grass or trees. If you create the soil and moisture conditions that will support tree or prairie growth, the desired should be able to outgrow the sagebrush. This is a process that takes time. Ask your consulting forester to explain the principles of plant community succession, and then my suggestion will make more sense. Best of luck to you! I'd love to hear how your forest turns out!
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