Not the cheapest but absolutely superb trees in pots at Costco. They're typically about 6 or 7 feet high, with four or five well developed branches - so I guess two-years old.
£11.99 each.
I couldn't resist a Reine Claude, but they also had:
A dark blue plum of a variety unfamiliar to me
Victoria plum
A red cherry
A black cherry (I assume a sweet one, not a morello)
Jonagold apple
Comice pear
A nectarine (some hope)
A peach (even less hope)
Sorry that I can't remember all the varieties, but if we had the space I'd have bought a truckload!
Similar in Lidl at the mo two for £10
Believe me, these are not the same as the ones sold by Lidl, Aldi, or Morrisons, excellent value though those are.