Where can one purchase Shark Fin Melon Patch cucurbita ficifolia seeds?

You can buy them from jdhudson seeds. Shark fin melon is also known as chilacayote.

http://www.jlhudsonseeds.net/VegetablesO-Z.htm

You can also search for them on eBay under the names "Lacayote" or "Chilacayote".

Apparently eating this melon is also helpful for diabetics.