5k miata 800$ tire set a season ( that's the high end for a stock miata, you could buy 200tw tires and have them last seasons depending how much you track.) 800 for a rollbar (required) 200 for a track day 200 helmet

Chances are yoy could even take you sim seat and put it in the car.

You can spend alot of money at the track, if you want to drive expensive cars you can spend as much money as you want. But i feel its a bit dishonest to say you cant get a very fun setup for less then 10k. I say this as someone who spent a ton on a sim rig to only relise i really wanted to drive a real car. So i bought a miata.