The American Seeds catalogue offers asimina triloba pawpaw products from trees noted for superior flavor and size.  Pawpaws, also known as Indian Banana Trees,  are NOT PAPAYAS.  Though the leaves are tropical-looking, the trees thrive in temperate-climates with a hot-humid-summer and a cold-winter to produce a delicious and unique-tasting-fruit in late-summer as well as attractive-golden-leaves in the autumn-season.  
If you are new to growing pawpaw trees you should begin by reading Selecting and Planting Pawpaw Trees.

***NOTE (01/20/15): The Pawpaw Planet Web-Site is the new source for everything about pawpaws including nurseries and international growing information.
The catalog has the following pawpaw product offerings:
5/30/12 announcement:    England's Nursery in McKee, KY is authorized to sale Kentucky Champion (TM) grafted-seedlings for the 2012-2013 seasons.   Please contact Cliff England on the availability for domestic and international shipments.
6/06/13 announcement:  England's Nursery has agreed to distribute grafted Kentucky Champion (TM) seedlings through 2015 when they are available.