Skateboarding isnt expensive but it also isnt cheap. If you follow sales and budget youre money accordingly its fine. Yes there have been ties in my life where I have gone to my shop to rummage through the used board stack or go used shoe shopping in thrift stores but compared to other sports skating isnt that bad.
For example, my girlfriend does volley ball. I always thought volley ball, basket ball, and soccer were the cheapest sports. With volley ball she has to pay a membership to a gym to play as well as pay league fees, both of these are done annually but if you break it down theyre about 100$ a month give or take. Next comes these special required court shoes for playing volley ball that are like 110$ and if the sole of them wears down too much then you cant step on the court or risk injury, basically they need to be in a certain condition in order for her to play. Id estimate that she goes through 1 pair of shoes every 3 months so thats like another 35$ a month. All that added up comes to about 135$ a month.
For me with skating I only go through boards about once a month maybe every month and a half depending on how much skating I get to do. I would guess that I go through shoes every month also. Assuming im paying full price for shoes (75$) and a 50$ board I'm only spending 125$ a month
But this is different for everyone. I dont skate big gaps or any serious impact stuff too often so i can generally make my shit last longer than some of my friends who go through a board a week