Wow, what a rip, I thought I paid too much. They are very common, and if you don't mind waiting, I'm sure you can find them cheaper than TSC. They probly cater to companies and contractors, where they can get away with that price, I found this with Fastenal, but I still buy my specialty bolts from them.
Your kart looks like a 3203, but its a bit iffy since the roll bars are removed. If you plan to use the 212cc predator, I think you will need a new torque converter, the 30 series is a great match to the 7hp, but if you plan to hop it up very much, it too will not handle the power output. I believe the limit is ~8hp for the 30 series.