How do you arrange initial legal support for cheap?

Some startup ideas require legal process flow clarification to make sure that the process flow offered by the startup is legal and complies with all regulations.
For example, how do you provide mortgage in USA? How do you provide exchange services in Germany? How do you legally provide services of drinking partner in Russia? (jk, but who knows what people might need ;) )

To summarize, at the idea stage, the legal aspects are often unclear and need to be clarified.

Where do you get preliminary legal support for a startup idea at the initial stage, when no funding is available? It has to be free or cheap, or something the startup owner could do by himself.