Carbon Dating and a Stuffed Raccoon - S2-E7
Continuity mistake: Sheldon places his membership cards down on a flat surface. He puts Radio Shack first, followed by Star Command, almost entirely covering it, leaving just a small section of red along the top. When the shot changes to a wide-angle one, the Star Command card has moved down and more red is visible above it. (00:01:00)
Answer: It's as simple as money is tight, it's not "George's money", it's the family's money so the expenditure was selfish.
MovieFan612