Hi Twinturbo, the kart is a toy, it is an old indoor kart I modified for my two boys to use. I used to race rotax seniors for 3 years. I gave up as it got a bit expensive and at my age I wasn't going to become a formula 1 driver...
The cheapest class I think from memory for youngsters starting is the Honda class. Sealed engines so it makes for exciting racing.
I bought an ex BT box from a transit and put it on a caravan chassis, that is now home for all our toys until the roadster is finished.
UK Karting website is a good place to get some good deals on used equipment for beginners. Good luck.