Hello Margaret, I'm actually answering two search-questions with nearly the same answer... Looked through some nursery catalogs, then went to the latest and greatest tool for such things;
The Internet, and searched "
Google" via
AOL. I went "3 pages" deep looking for a
Mirabelle Plum tree; it sounds like a great plum! ...could that be the reason there's none to be found..?
I've never knowingly tasted one, and you've peaked my interest, but I'd left this question open so someone else could take a shot at locating it... and I've wanted you to know "we tried!" Sorry

I couldn't help you "this year" - but you know what that means ~ there's
always next

!