I'm currently looking into digital whiteboarding solutions, Miro & Mural seem to be the tools of choice, but both are so expensive that I'd rather hold my nose

I'm currently looking into digital whiteboarding solutions, Miro & Mural seem to be the tools of choice, but both are so expensive that I'd rather hold my nose and wait for Microsoft to invest in the Web Version of Whiteboard instead of spending another 4000$/yr on a SaaS App that gets used by 5 people 2 times a weeks and 30 people once every quarter...