Okay, you have a decent starting point. I don’t know how much time driving on the simulator is going to help if I’m honest, theres a lot going on in a kart that you can’t get from a computer.
Unfortunately, sponsors aren’t incredibly prevalent in karting. It’s just not a huge market for them. You can definitely find some, but it’s not easy or common. I wouldn’t worry too much on sponsors but just work on being as competitive as you can be, sponsors or not.
Mechanically you’ll probably have a decent starting point so I wouldn’t be terribly worried about that.
Budget wise it sounds like you’ll be fine. Used equipment under $4k should be easy enough to find and $1,000 is plenty for safety gear.
You shouldn’t need new tires every raceday for a club. Probably every other in X30, and you can go a long time on tires in KA before they have to go, probably 6 to 8 races if you’re competitive up front.
Everything else shouldn’t get to $500. Race entry is like $60 at New Castle, gas is probably $15 for 3 gallons as a rough estimate, I have no idea how much gas you’ll use on a typical race. As long as you dont crash that should be all the costs you have, although having the extra money as a backup will be useful.
I do recommend 206 still. It’s definitely not a rental kart and you’ll learn a lot about carrying momentum and racecraft in a pack. Once you have those figured out, driving a KA or X30 could just be applying those principles with more power. It’s a cheaper way to learn the same stuff, and while there would be a learning curve going from 206 to one of those, in the long run it would be beneficial.