Substitute for whole wheat pastry flour?

[wondermilky]

I'd like to make the Peppermint Mocha Trifle from Hannah Kaminsky's Vegan Desserts book, and I'm at a loss for what to do about the whole wheat pastry flour. I have a little bit of *white* pastry flour, but it's hard to come by and expensive, and from my Googling it doesn't seem like an easy substitute for whole wheat pastry flour, anyway. I'm on a tight budget and prefer not to buy whole wheat pastry flour because I wouldn't use it much. Does anyone have any suggestions or tips on what to do for a subsitute?

Thanks for any help! ♥