Waiting for bus tickets to get cheaper is my go-to budget hack.
I mean, I travel on a tight budget all the time. I saw that bus and train tickets often cost less if you buy them near the travel date. For example, my trip from Berlin to Prague had tickets at 30 euros when I looked early. I waited, and two days before, they were 15 euros. That saved me half the price. This works with some airline sales too, if you can risk it. It's all about being okay with not having plans set in stone.