I think the only way is to make this a $1 per months game(first months free) or allow a $10 per year contribution and the several hundred people that play this would cover the server upgrade.
I
really am against the idea of making it paid. I think that will massively reduce users. I, however, would be happy if Patson implemented ads into the site. It perhaps wouldn't be much but every little help. I also wonder if they could ads small
non-game changing premium features. I want 0, imbalance with people who pay/those that don't. I'm sure most would agree. Perhaps charge small amount's for a one-time payment to do things like unlock a dark mode, or change the name of your Airline. Just other methods to monetize the site. I wonder what his thoughts would be on that?
Either way, I think to make the game cost would severely damage the community.