How can I develop and support mainframe software without going broke? Mainframe (zOS) software is still very much in use right now. Many of the most critical applications of banks, insurance companies, airlines, global companies, etc are running on (good old) mainframes.

However, for companies that are in the business of developing and supporting mainframe softwares, it may be (terribly) expensive to have the required infrastructure for developing, testing and supporting such software.

What are possible solutions for developing and supporting mainframe software without paying fortunes for the required infrastructure (and spending all software revenue to it)?
One possibility would be to find a 3rd party business owning such infra and selling on-demand usage/access time/connectivity to it as a service for more convenient expenses. For example Mathru Technologies (found through plain google search).

Another possible approach is to obtain such services from strategic partners or maybe even your very customers. Maybe even for free, depending on the quality of your relationship.

You could also ask the mainframe community for advice and/or leads in this direction.