What level of skill is required to build the buggy?”
If you haven’t welded before, or don’t have a friend with a welder, it may be more difficult. There are welders and fabricators situated all over the place though, so check your local directories for someone nearby. Here’s an example of how your welding should not look like. This wishbone was for a home-built road car in the UK. I don’t know if it ever passed SVA. Apart from welding, all that’s required are some tools, a good helping of common sense, and the ability to read and follow instructions.