I bought a ship on the Galactic Market today. My credit transactions shows I paid for it, and it entered my inventory page. I was the happiest sentient in the galaxy.
Now it's not in my inventory anymore. It totally disappeared within half an hour of the purchase.
It was probably the result of a bug that it was on the Market in the first place, and the admins have returned it to its rightful owner. You should try emailing them with the situation and letting them know how much you paid so you can be reimbursed for it.