Best humble bundle I ever bought was a $15 bundle that included Euro Truck Simulator 2 because I wasn't sure if ETS2 would be fun enough. I've since purchased every map DLC, American Truck Simulator and every map DLC for that too, plus a smattering of the cargo, truck and paint scheme DLCs, and I'm very likely to continue purchasing the DLC that keeps the studio constantly updating these 10+ year old games at a really healthy pace

The first and only humble bundle I've bought was the WB with all the Arkham and Injustice games in it. I already owned like a third of the games, but I wanted the rest because it also had Mad Max. And it was only $12.