Start with what you have. A modern phone shoots more than well enough to earn; chasing cameras before you have a routine is procrastination dressed up as preparation. The three upgrades that genuinely move the needle, in order, are better light, a stable tripod or phone stand, and clean audio if you talk on camera. Everything else is optional for a long time.
Buy slowly and only when a specific limitation is costing you. A tidy, well-lit phone setup beats an expensive camera you have not learned to use, and it keeps your money where it belongs early on — reinvested deliberately, the way Business, Money & Taxes recommends.