Saying “I can’t afford that right now” to friends is honest, not embarrassing. Good friends adjust.

Money silence is expensive. Saying nothing means you either go and feel sick about it afterward, or you invent a reason, and inventing reasons is how people slowly drift out of plans. Saying the plain thing moves the conversation to something cheaper, which is usually all anybody wanted anyway. Most people your age are in the same position and relieved that somebody said it.

Have the sentence ready before the next group plan, and say it without apologizing twice. Offer an alternative in the same breath: the park, your house, next payday. Notice who adjusts easily, because that tells you something useful about the friendship.