In the mid 2010's I got back into tabletop gaming in a big way with D&D Next. I was running games all the time and most of my friends wanted to use grids and miniatures for combat.
Sadly I had sold all the dungeon tiles I'd used in the days of D&D 4e, so I needed a cheaper solution. What I ended up doing was making my own dungeon tiles out of cardboard, stone texture paint, and hot glue.
These were a total hit at my table, and because they were modular I was able to make a ton of different dungeon designs. One thing I like to remind new Game Masters is that you don't need to spend a ton of money with this hobby: sometimes the best tools are the ones we make ourselves!