"This stuff is so collectible because everybody knows it's never coming back, " said Thom Nulty, a Santa Monica, Calif.

WSJ: Airline Collectibles Take Flight

Terry Nulty, CEO of ZDU, Ziff-Davis (ZD) ' online education unit, had Rosenthal's help building ZDU before Rosenthal joined Kaplan.

CNN: Kaplan is starting an online college -- minus the keggers

"The biggest challenge Bill faces is how does he defend Kaplan's position in a space where they're not as well known, " Nulty says.

CNN: Kaplan is starting an online college -- minus the keggers