How to use Microtransactions

How do you make microtransactions? Is there a tech that lets you do this or am i just missing something?

If you open a shop or flightpath, you can set under “Options” pay Gold or Real Money.

I checked the options panel and it is completely empty for me at all of my shops.

It’s actually the “Service” tab, here:

The “Cost” option lets you set what it costs to interact with the building. In the case of a blacksmith like this one, it’s the cost to buy a new weapon. You can set the cost to be either Gold (in-game currency) or “Real Money” (dollars), and can also change the amount.

I guess that did not occur to me. Thanks!