I know I've already spent a few fortunes on concert tickets ;-)) However, we also go to "hat concerts" where admission is free and you end up collecting for the artist...

Events like night walks, apart from perhaps travelling or preparing for picnics etc., are free and unforgettable at the same time.

I once celebrated my birthday with my children at a lake when they were still quite small. We had travelled there the evening before, with sleeping bags, blankets and a campfire on the beach. It was cosy and adventurous to sleep under the stars. In the morning, when we woke up relatively early, a family of nutria had made themselves comfortable between the sleeping bags ;-))) Sweet as sugar!
Money can't buy it...