CRC and IRS both make some. I've ran a L3 and a L4 both without them for a long time. They just allow you to run tires down smaller. I did break down buy a pair finally. I can get another race or two out of a pair of tires. So they will pay for themselves eventually.
Everything that was mentioned is nice to have, but you can run the car just like it is and be VERY competitive. I've said it many times on here, 12th scale is mostly the driver behing the wheel. Setup matters, but until you can wheel the thing perfectly, I wouldn't worry about it.
Just my $.02
take care
john