I can only say that it is surely vastly different from region to region and club to club.
If you include the Bayernliga as a regional league (it is right below the Oberliga Süd), then there will be players throughout the regional leagues who earn as much as they could in the Oberliga. In some very few cases, maybe even more depending on the local sponsor and ambitions of the club.
But rest assured that most all regional teams are playing with amateurs, some may even still be paying to play. Usually the one thing that a team can offer most of its players is to play free of charge and to receive a certain number of sticks and perhaps even a set of equipment. Various suits and ahtletic wear goodies are often part of the package, but you often have to turn that stuff in once your time with the club comes to an end.
There are surely several very good German players and even more foreigners playing throughout the various regional leagues who are getting 2+ k per month to play plus a place to live and either a car to share or a paid for ticket for local public transportation. They may also have their plane tickets paid for to fly in at the beginning of the season and then away once the season is over. That's more than some guys get to play in the Oberliga where it is not uncommon to simply get 600-800 a month plus living accomodations and transportation.
Again, how professional the team is run often depends on the club structure, what money comes in, and if they can find sponsors or have a major donor to carry some of the larger costs (namely player fees and/or things such as team busses).