You'll spend 80.000G in stadium maintenance (will be more in global, you need to include other facilities later), however you'll receive more money too!
If you upgrade your stadium to Good quality, you'll receive 220.000G every league match you play there, and your team will be stronger in league home matches.
There's a real profit when your staium is upgraded to Very Good Quality, not before..... until then, stadium maintenance increases 1G per seat and incomes increases 1G per seat every level.
Stadium quality makes your team stronger, it hasn't been planned as an income source.
If you want to increase your home matches income, you should upgrade your museum first, and upgrade your stadium capacity to 20.001, and, when attendance crosses that "20.000" barrier, means you have enough rating to take more people home. Then start to upgrade your stadium's capacity.
