Why not grow one from seed and see it if is hardy in your area?
That way you get the enjoyment of eating a Cherimoya and avoid
the expense of shipping a small tree.
I grew a few seedlings and tried grafting "Fino-de-Jete" on
them and it looks like the scions have turned black.
Oh,well, there is always next year. I have planted a few more
seeds and will try again.
I have an "Elixer" growing here in Southern California, 3 miles
from the ocean. It is about two feet high and I hope it will
soon have some new leaves.
Julia Morton in "Fruits of warm climates" says
"The cherimoya begins to bear when 3 1/2 to 5 years old".
http://www.hort.purdue.edu/newcrop/morton/index.html