I would suggest that it depends on whether you are planning on doing the work yourself, or whether you are doing a quick broadacre installation. In my limited
experience there is a place for both approaches, but gradual transitions seem more common than rapidly transforming whole landscapes. the advantage of buying trees is that they are available NOW.
I've been gradually transitioning our garden area to
permaculture food forest, putting in a few trees each year and mostly propagating my own plants - I have little free time and I'm not in a hurry. One thing I have found is that it is not much more time consuming to propagate 100 plants than it is to produce 2. I've struck big batches of currant bush cuttings for example and had very good success rates. With
apple trees it is a little harder if you want known varieties, but you can use stooling to produce
root stocks and grafting to get the variety.
If I wanted to produce 1000s of
apple trees and had time to do it myself I would:
Buy 10 known root stocks that are well suited to your conditions and growing strategy - modern orchards seem to be growing dwarfing trees, but these need a lot of pampering and are not so well suited to typical permaculture strategies. I like something with a good root system so I don't need to water, and a strong enough structure that I don't need to stake it!Plant the stools in good soil, thoroughly mulched with wood chip and allow to grow for 1 yearIn winter cut to ground levelPut a large bucket or pot with the bottom missing over the stool and fill with damp sawdustAllow to grow for a year - multiple stems will shoot and grow through the sawdust, rooting along their lengthIn winter remove the bucket and shake loose the sawdust, use sharp secateurs to remove the stems with their root systems in tact - you should get 10 or so new rooted apple root stocks per stool
You can either bench graft these apples, and plant them out, or just plant the root stocks and graft them in the field at the appropriate time of year.
Using this approach you could establish 100 new apple trees per year - a lot more if you use your first crop of rooted stems to establish more stools. Time invested in this process is minimal... perhaps half a morning to plant the stools initially, an hour to cut and mound them up with sawdust, an hour to cut 100 odd rooted stems... perhaps half a day to graft them and plant them out. The slow bit is that all this work is scattered over a 2 year period! Over here it would cost me £5.00 per grafted tree or more so the hourly rate for doing it myself would be good, but I'd have to wait for them to be ready.