What if one of you took it over for a fraction of what is being paid to the management company? If you're paying ($400 x 20 homes) $8000 just for the management, would one of you do it for 1/3 of that? 1/2? How much work is there, really, for 20 homes?
In our HOA, we all kind of cycle through who is president, VP and treasurer. I mean, it gets voted on, and those who are voted in kind of reluctantly accept it, but there isn't THAT much to do except for treasurer — we have 62 homes. But their pay is no HOA dues while serving. That's it. As a result, our HOA fees are $25/month, and that covers taking care of three parks.
We actually hired a member of our HOA to take care of the parks, too, and they do a fantastic job for a fraction of the cost of what it was costing to have an outside landscaping company to it.