Being the frugal sob that I am, I am looking to prepare a good number of perennials, shrubs and trees for a food forest. I expect that actual in ground planting will be a few years out which gives me time to buy small and let them grow and/or buy one and propagate off.

If it makes sense, would like to avoid planting in-ground, especially the trees. I see these air-pot units and they seem like something that could be used to accomplish my goal.

Has anyone used them? Alternative tactics?

Do you mean those 3d root air pruning pots?
So far this is the best system i've seen in regards to that, but I don't think it will meet with your frugal criteria.

http://trentcom.com.au/

I'm looking big-picture wrt frugal. $15 for a pot that I've rooted a cutting is way less than $45 for another cherry tree.

If your going hard like that you might have the warbucks for peter lawtons system, it's mainly the flood trays that save on water and manage the plants that set's them apart. The elite roots system produced by 3d pots are bar none the best way to go into nursery production for yourself or in surplus sales, I'm look at this for myself. I can't imagine being able to produce competitively and buying in another growers tree's you don't know, I dont even see it as frugal but simply critical. Check out this video of the scale he's working on in his home setup, 10 racks to me is a serious small scale system. Being able to grow tree's on to the advanced stage without root retardation is just another level of certainty you can operate on that others can't.

http://www.youtube.com/watch?v=0c7FyujVNP8
give me a critique of his system, I havn't been able to find much nasay to really put my idea of this systems viability to the test.