How should I plan to afford this?

I have learned over the course of my (not few) years that you should adapt your wishes to your life situation. It makes no sense to wish for a loft if I can’t get out of my village with farmhouses.

So if building land in and around Munich is so expensive that you can count yourself lucky to get and afford even 250sqm, then I wonder why anyone wishes for 500sqm. Hmm, probably to also fit in the double garage.
An apartment for tenants is not a given either.

Yes, of course a double garage is supposed to go there. Why not. With two residential units, that is okay. Maybe smaller after all

I would also immediately include a pool

I know someone who also looked for existing properties in the Munich area for some time. They have now bought a house for €450,000 - not old & up-to-date. Maybe you will find something suitable on the real estate market after all. You should get in touch with a real estate agent.

"keineKohle" in connection with Bavaria is very bad. You can put down 300,000 EUR for land (good luck), basement, and granny flat. But then the house is missing. Anyone who tells you otherwise is simply filling their pockets. Seriously: We are building in Saxony.. currently at 350,000 EUR without land, without basement, without exterior facilities, including incidental building costs.. but still before the selection phase.

Regards, Steffen

We already have the plot and are building with 350TEUR in solid construction with a usable basement and 140 sqm living space (excluding basement). The 350TEUR includes ancillary building costs as well as kitchen and inventory and also some nice frills, all of this also in Bavaria.