For many people those top of the range or latest models of go karts are out of reach due to their cost. But there are cheaper go karts for under $100, small karts like the Razor that can give you many hours of happiness without breaking the bank. However when you take a closer look at such go karts you can see that other costs come up because of its cheap design that then push the over all cost higher.
These karts have a simple design. A go kart flat frame on a wheeled skateboard with an accelerator on its handle bars that you steer with and brakes. It is made using parts from electric skateboards and bikes and runs on electric so it can be recharged. This means it is not as powerful as other go karts, it has a more limited ground clearance, and needs to avoid grass and rocks or it will get caught up in them. Also the battery these go karts use have a limited life and can burn out easily. So while you may pay under $100 be prepared to pay around $60 or more a year on battery replacements, (the amount will vary depending on how often you use the go kart).
A great alternative to a metal framed kart and one that is less costly too is a wooden one. It is able to handle steering systems, larger engines, disc brake systems as long as it is designed carefully and properly. Another handy thing about building and maintaining a wood go kart for under $100 is that wood tools are mostly all you need, which themselves are cheaper in general and easier to source. The actual components are not that expensive either like the clutches, chains or disc brakes. Of course the rubbing braking system is not as good as the newer systems but it was used many years ago and was good enough then!
A wood kart can be made in a weekend if you want, or you can make it an evening thing over a few months. Looking for something to work on for the winter while you bond with your son, build a wooden go kart. By spring time it will be ready to test drive! How complicated you make the steering system on karts under $100 is really up to you and how much of the budget is left. There is the supported bogie system and there is the Ackermann steering system, people can argue for each one and why it is more efficient so that may be worth more research unless you already have knowledge and have a preference.
Go karts for under $100 are a lot easier to make, are the type that beginners are more likely to turn to and can be made using components some people might already have around in tractors or even lawnmowers. There are also plenty of junkyards out there with many use-able parts like wheels and rims for not much money. Other places you can look for second hand cheap parts are Free Cycle and Craig’s list. One riding lawnmower has all the parts a wood go kart needs. But do not be tempted to just use that lawnmower – it is not stable, it is set too high to be safe and there is a good chance it would flip or roll.