You can find it at www.mountainmaples.com, which also has Tsuma beni, a similar variety.

I've been happy with my orders from World Plants.
Good luck,
zube

Here is a link that might be useful: Tsuma Gaki at World Plants

Eastwoods Nurseries in Little Washington, VA, carries it in 2 sizes: #1 $38.50; #2 $55.00. Their catalog is more extensive than the website, so if it's not on the site, just contact them. They have more cultivars than their website can hold.

Link to their website is below.

Here is a link that might be useful: Eastwood Nurseries

Thanks for your help folks! I've read so much about this variety, and have yet to see one at a nursery around here. I'll order one in the fall.