While they are being used in this military-contract role, they are not common in the hands of private individuals in North America. That big engine is thirsty, and it is "a lot of jet" for the average warbird aficionado.
For G.A., the most popular jet warbirds are likely the L-39, S.211, T-33, and Jet Provosts/Strikemasters. It seems that L-29's have gotten somewhat scarce as compared to 8 years ago.