I've refrained from collecting the kei apple because of the need of two sets of plants. I do have the hybrid Dovyalis hebecarpa X abyssinnica aka Tropical Apricot var. Prodigal which is supposed to be self pollinating. I see many blooms this year on my plant so I've got my fingers crossed for some fruit.
If I were you I'd get a few more plants, grow them out them out to sex them.
Conversely you could try and get a hold of Exotica Nursery out in California where I saw that they had male & female plant sets available.