if you buy a ceo, you are looking at spending 80 gc minimum.
The price of the corp 50gc + the regs for the month 30 gc.
For 30 Gc you could start a new CEO and use the extra 50 coins you saved filling it up with corps.
This seems a better option than buying, even at minimum, because you can customize your ceo to your needs and gameplay. Besides if you want one for game levels, just start a new one. Buying OR selling a country or ceo will disqualify you from rewards for at least 30 days.
So, just start your own. Chances are you can build something better than you can buy with 50 gc. This is not always true with countries however. Hope that helps.