What amazes me is the fact that you can now pick up an airworthy L-39 for less money then a late model Cessna 172.
What REALLY amazes me is that you can pick up a '80s L-39 for less money then a 70's Super Cub, hmmm. 380mph cruise for $90k, or 90mph cruise for $120K. (I'm just bitter because I want a Super Cub, and while resale value for most single engine pistons have plummeted in recent years, Super Cubs still fetch a premium)
The problem with L-39s is affording to feed and maintain those turbofans.
Nail on the head in the last sentence.
You get what you pay for. An older airframe, especially an older eastern bloc built airframe gets very costly really quick to keep and try and maintain. While parts abound, costs are a rising and the only guys really operating these birds these days have deeeeeeeeeeeep wallets. That means for the layman, they are nigh impossible to afford without group purchasing. That is simply a recipe for disaster when it comes to high performance jets.
I had the chance to buy a very nice Fouga a few years back and I passed. The reason, cost to operate, continually maintain, and the kicker we have not touched on until now, maintain.