you can start racing karts from the age of 9, and go from their.
i started when i was 9, my dad done everything he could to keep me in it but even karting was expensive. we used to turn up at the track with the kart in the back of he's xr3i and set up the kart on a black and decker work bench

proper shoestring budget, even used to rummage through the skip at the end of the day for tyres!
as chip said you need lots of money to get anywhere in a series like that