Inky, A bird is going to go the highest point possible. It does NOT matter if your short or tall or even in a wheel chair. I have not seen a bird yet that won't at least try to get to my shoulder, it is just a bird thing. You don't have to put the perches up so high that you can't comfortably reach them, but if they are high and you go to the cage to get the bird out, it will come to you as you open the cage door. Birds adjust to you, just as you adjust to the bird. Some takes longer than others, but since you are getting one from a baby, it should be easy. Birds are smart little critters, it will recognize your handicap and understand.
I really think, that you are worried to much about your disables, just remember if there is a will, there is a way.
Yes, pet shops suck, they have no attachment to the pets, just a dollar sign.