Hi mate, I also going to start my racing career and karting this summer.
I will drive in a used 1998 TonyKart chassis(rather old:razz
and a used KT100 engine. Actually my budget is very limit and racing in China is not cheaper than racing in US so I can only buy some used engine and chassis. In my opinion KT100 is a good engine to start, but I don't know if it is available in America.
Buy the best safety equipment at your budget, and make sure the helmet is tight. And please pay attention to the money for fuel, tyres, rebuild, etc, these money are no less than buying a kart.
Well i haven't involved in karting actually, i just get thoese information from a friend of mine, who is a racing driver, so i'm not sure if they are right. Ask the local racers or mechanic, and you can get the right information for your region. But be careful when you are asking the people who is going to sell you something, they can cheat you sometimes.