Answer by Thomas Zerbarini:
First of all, private jets are a complex and very sophisticated machine. A lot of care and craftsmanship goes into each aircraft. On the surface private jets may seem to be expensive; but, if you factor in the productivity of a private jet(s) to a company or person, the cost can easily be justified and even cheaper and more productive than using commercial airlines or charters.
for some basics on owning and operating a private jet. you'll see they conclude that the yearly cost for "operating" a mid sized jet would be around $2.5 – $3 million. Acquisition costs would be more.