You need a tenant union. There may be tenant unions active in your area which you can contact for advice, or even support. Beware of retaliation though. This is something which needs to be thought about carefully and approached strategically. In this regard, it is no different from unionizing a workplace.
If the corporation is renting 500+ units, that means they are ripping off 500+ working class families / individuals. If those 500+ tenants organize to the degree where they can collectively withhold their rent, they’ve got the landlords by the balls. Individual action can only go so far.
Here’s one perspective: https://runyourown.social/
Personally, I run a Mastodon+Hometown server for around 100 people and it costs me about $30/mo. It costs me more to fill my car’s gas tank. I could maybe start a patron or something, but at this stage, it is not even necessary.
About 3 years ago, I was a member of r/ChapoTrapHouse, which got banned from Reddit. The day after this happened, we had over 10,000 people sitting in a lifeboat Discord “server.” Within the community, we had the experience and willpower to take Lemmy, kick the tires, make a couple adjustments which were necessary for our community, and make sure we weren’t doing malpractice by hosting it. This all happened before Federation had been implemented in Lemmy.
Maintaining the fork was labor intensive, and a lot of the original developers burned out. We couldn’t afford wages for development (the site still only exists due to volunteers), but the hosting costs were easily covered by user donations.