Missing Career Aircraft for Purchase

There are some aircraft that I'm certified for that are not avaible to buy. I'm thinking of turboprop planes and jets. I've done the certifications, and I'm flying them as an employee. I don't have enough money, but I don't currently have enough money for a new Cessna 172, but it's showing up to buy. Am I missing something? As always, thanks, in advance, for the help.