I gave away a small fortune on "better" paintball-guns and things; you can buy the paintballs in different quantities. (100~300~500~1k) Before a tournament I would buy 2 cases of 500 and I think each case was $50 for the good stuff. They will up-charge if you buy at the field.
My entry level P-gun was less than $100 when I first started, and I soon wanted to level up for better accuracy and range. I went up to a $200+ P-gun then little later my 3rd was a custom with select speed and fire rate, ammo counter and a few other bells & whistles. This isn't counting the money you'll spend on the best auto hopper so that the balls don't clog and can keep up with the faster rates of fire.
That leads to needing to get away from the standard C02 tanks and upgrade to a Nitro-tank and Remote-Coil and extra gear to hold all that stuff while you're "running & gunning". When things break/fail like the O-rings or whatever (and that's a constant thing) you're going to want the best like polyurethane O-rings not the rubber ones that expand and break easily then leak air. Before I forget those Nitrogen tanks are more expensive because they can hold around 3000 PSI ~ 4500 PSI. More pressure means much more consistent shots over C02 especially during high-speed shooting which brings needing a fast auto-hopper into play.
If you got money to burn it's defiantly fun for a while, just try not to get hooked like I was for 2years or be like a guy I knew that spent $400+ on a at the time new Autococker and the thing was a POS. He spent more time cussing and having a fit trying to get it to work properly than shooting playing. 🤣😂🤣