It's not just the paint bill, the infrastructure costs would be more per team. For a "normal" tourney, you'd have something like 40 odd teams playing on 4 fields, but with X-ball you would fit a lot less teams on the same 4 fields over a day. The cost of setting up and running the event e.g. scaffolding, netting, rent of the site, admin etc, which is a big part of the cost and pretty much constant however many teams enter, would then have to be split between a much smaller number of teams. Then add the reffing bill (around £3-500 per field depending on number of refs, how much you pay them etc) and divide THAT between less teams, and the cost to a team before they've even fired a shot goes up by a very large amount.