Moscow is a wonderful museum of art outsiders. working there (at least at work when the last time I was there) are very nice people. may be, they ask, they probably know people who collect such works.
http://www.museum.ru/outsider/about.htm
good luck to you!
a mockery of mentally ill people do not - as we know, "from the bag so the prison (and the mental hospital) does not reject." no one is immune from mental illness.