Easy sour cream recipe

I have some recipes that call for sour cream, but sour cream isn't cheap in my place so I sometimes feel hesitant buying it. Another issue is that I am seldom able to consume the entire cup - a total waste of money! So I thought I should try to use sour cream alternatives that would yield the same result in baking, but use cheaper ingredients. I'd also like to try sour cream substitute on recipes that call for yogurt because the yogurt that I get in my local grocery stores contain gelatin and I *think* the gelatin is making my baked goods rubbery.

Here's an easy sour cream recipe from The Frugal Chef  that I'd like to try: