I do not know of a source for these snails, but I can offer a suggestion. Sprinkle hot red pepper over the plants. I do not think the snails will like it.
Also, you could spray garlic pepper tea on the plants, or hot pepper wax might even be better as it is less likely to penetrate the skin. The product description states that it will not penetrate the skin of fruit, but Strawberries are not exactly thin-skinned, so you might wish to contact the company before purchasing their product. There are other brands, but here is a link:http://www.biconet.com/botanicals/hpw.html