Fortunately, fried green bananas taste very similarly, and can be made very cheaply.
I tend to buy bananas from the reduced rack, because even in season, their price rarely seems to get down very low, and especially considering the fact that a large percentage of the banana gets thrown away, making it cost even more per pound than it would appear at first. Buying from the reduced rack allows me to pay as little as possible for bananas, and most of the time reduced rack bananas are brown, mushy, and overripe, which work amazingly in dessert recipes and either eliminate completely or drastically reduce the need for sweeteners in recipes.
Sometimes, though, the bananas I buy cheaply are green, and aren't just being sold at the regular price, left to ripen, because they got nicked or similar, and therefore they won't necessarily ripen completely. When this happens, that's almost better, because green bananas can be made in recipes that call for green plantains, such as fried green plantains or bananas.