If you have little space available for fruit trees, there are a few options.
You can buy trees on dwarf rootstock. G65 is a an extremely dwarf rootstock for apples that only gets 4-7 feet tall.
You can also summer prune trees to keep them at a low height. I keep all of my fruit trees under 12 feet, simply to make harvesting easier.
And if you want to get fancy, you can also graft multiple cultivars or varieties onto a single tree. One of these days when I have some time for it, I want to graft an apricot, plum, pluot, aprium and peach onto the same nematode resistant root stock, simply for the novelty of creating a "FrankenPrunus" tree.