There seems to be 2 or more purple potatoes.
White with purple flesh and purple with purple.
This page has seed potatoes.
http://www.sandhillpreservation.com/Plants%20&%20Roots.htm#SWEET%20POTATOES

There is a produce company in Calif. that carries these.
Go all the way to bottom of page.
http://www.dorevaproduce.com/varieties.asp
Also do a search on the Vegetable Forum. Someone there metioned having slips of the purple/purple.
Also I think the ornamental potato 'Blackie' is the same thing. Either that or the pink and green variegated.
My friend from the Phillipines mentioned it once.
I'll check with her tomorrow.

no...the ornamental blackie isn't... that is a different one. I found it at Glasshouseworks, so the problem is solved! Thank you for your time! I am going to check out the produce place right now.

S. Facciola (Cornucopia II) lists it as 'Okinawa', says the flesh "changes to a lilac-magenta color". Also notes that it is "Somewhat of a shy bearer in California, producing roots spottily and away from the center of the plant."

Another one he describes as having "flesh deep purple when cooked" is 'Mexican Purple'.

He indicates Exotica Rare Fruit Nursery, Vista, California as a source for both (as of 1998). Sand Hill Preservation Center, Calamus, Iowa is also listed for 'Okinawan'.

We found these wonderful tuber at the Framers Market in Hilo. Am looking for a source for them on the west coast. Would like to try growing some in my greenhouse.