You can get snowpear juice from all supermarkets here in Thailand. It's like an apple crossed with a mega juicy pear,sweet and a little floral in the smell.When you bite one they are like crunchy apples but with the juice content of a very ripe pear!
You could try looking in an asian food shop.
Supermarket juice wines are better with 2 or 3 litres per gallon, recipe looks ok to me, I take it you'll be adding pectolase and maybe citric acid, tannin and glycerin?