Turbines make the most sense up high; they burn too much fuel down low. High can be good: it can get you over weather, even if limited to FL250; you can catch favorable winds eastbound.
The tradeoff is, if you want to bring people up there, high requires supplemental oxygen or pressurization. With current technology, pressurization means heavy, complex and expensive. On the other hand, supplemental oxygen turns off most passengers. I doubt my spouse would do it often; I'm not sure I trust my young kids to keep a mask or cannula on for any length of time without constant supervision. In either case, none of them would look forward to a high flight for that reason.
Eclipse tried to do it for $1MM and missed the mark by about 100%. Cessna shortened the Citation into the Mustang and brought it in for about $2 MM as well. I was intrigued by the D-Jet and Cirrus Vision single engine jet ideas, but either need something more than the novelty of a jet to make sense as a personal transportation machine.