Frankly spoken - I'm thinking to start very small (with few users use case) just on my raspberry Pis. An investment into a hosts root server could be delayed at the early stage (Real servers are a matter for crowdfunding later on, if we attract enough aquarists). My own domain service allows me to use a DynDNS Service. This enables me to start very low-cost with a raspberry Pi setup even for the database in my home LAN (as SLAs not the highest prio at the moment).