Well actually a used military trainer jet is probably around $100 to 200k. What’s going to be shocking is the maintenance cost and finding mechanics with the knowledge and expertise. Plus those planes drink fuel like no tomorrow. An airfield near to me has 2 privately owned L39s.As for the UL39, our concept was quite similar, but we wanted it to look a bit more like the F-35 . Both for me and my aerodynamics guy it doesn't make much sense to copy something and use it in a completely different aerodynamic regime.
Just think, speed, Reynolds, weight, etc. all being completely different, so why not start with a clean sheet? In addition: the L-39 is said to be a good trainer, but my aerodynamic guy and test pilot has many hours in military fighter jets and he said that most military jets fly marginal at best. I myself had the pleasure of a few hours in a F-16 and Eurofighter full motion sim. I would describe them too as "behaving good", the same way as any editor of a magazine would too.
Still, the flight behavior of a jet is nothing that I would sell with good conscience to any recreational pilot:
*makes it absolutely impossible to slow down to landing speeds without usage of spoilers
- super high pattern speeds
- low drag combined with high residual thrust (>20% at idle)*
- large turbo-lag (5s!!! for the PBS, up to 20s for the real big birds)
- small margins (like max. gear speed minimally above stall speed)
This is why the Beast One is designed to counter this as good as possible. For the 2-seat version, we considered the PBS +fan solution even before the UL39 guys, but we went away from it. First, the TP-100 is in a price range beyond of 100k (I forgot if 110 or 150) but uncertified and with a rather low life, as the TJ-100. Second, we asked Daniel Schuebeler if they could supply a fan of this size, as we know about the efficiency of their fan systems. He declined and said, that they won't dare touch anything above 25kW as for back then (hard to handle the rotational loads, even for carbon). Third, we had some concerns about the vibrations of the shaft and fan, as you have to cover 240kW over a wide variety of rpm's.
So in short, we considered it too expensive and too risky as for us to continue... Also, too expensive for any homebuilder and most guys with the sufficient money like to go to the next step for a "real jet".
Hence a semi-home built/factory assist 2 seater kit jet costing 100 to 300k with 300kts flight envelope and not costing the sky to maintain will likely sell a few. Not many but maybe in the 5 to 10s a year.
By the way the graphics n your avatar reminds me of the Heinkel 178 or 176