Video games, especially online with at least 1-3 friends = hours of fun. My friend and I race on Forza almost every night, we just build cars that are equally good then race them and then build more cars and more races. Our shit talking and banter is so much fun. Granted you'd need a game system but it lasts so long it will pay for itself in entertainment.

Build something? A friend an I built a air powered wooden rifle once with stuff he had laying around completely free.

Pick up a cheap used acoustic guitar and learn to play.

Shooting range? For 2 people here $30 each gets you a rental handgun of your choice, 100 rounds and a hour at the range.

Board game nights are pretty fun, monopoly can become a bloodbath lol and twisting rules to your liking makes the games intresting.

Model building? I used to be pretty big into building model cars and sportbikes, relaxing, creative and some even have detailed engines n shit you can put together, it gets pretty complex with some of the masterbuilder models.

Its hard to find cheap entertainment nowadays but making the initial investment into a hobby can provide hours upon hours of entertainment in the long run. A few hobbies are really cheap after you buy the needed gear/equipment.