Cheap ROS for First Autopot Run?

Just popping my seeds for my first run (2pot), and I’m tired of messing with tap water and buying distilled water. Since I’m poor, I’m considering a cheap reverse osmosis system, but is it good enough? Is it worth it? Should I also pick up a resin filter? Does the resin filter have to be the same brand as the RO system?

Apologies for my ignorance 😔