There is a newish one in Korat which is under the patronage of the Catholic Bishop of Korat http://www.camilliankorat.org/index.php/en/
It seems rooms are around 25,000 baht a month for a single room and about half that for a bed in multiple room. Apparently they also do rest care at around 500 baht a night. The website is in English and Thai. Might be worth phoning them for further information etc.