The Vegas Renormalization - S2-E21
Sheldon: While my compatriots are in Las Vegas, I will be enjoying a blissful evening in my personal Fortress of Solitude.
Penny: That's Superman's big ice thingy, right?
Sheldon: You know, I'm in such a good mood, I'm actually finding your tenuous grasp of the English language folksy and charming today.
The Vegas Renormalization - S2-E21
Sheldon: That's preposterous. I do not resemble C-3PO. Don't get me wrong, I'm flattered. I just don't see it.
Suggested correction: Not being able to afford doesn't necessarily mean he doesn't have the money, especially a man like Sheldon. He works with a budget and he sticks to it. In his budget he has a certain amount set aside for rent, anything more than that and he can't afford it alone.
Nonsense. If he was sticking to a "rigid budget" he wouldn't have even thought of lending a hopeless credit risk like Penny a single cent. Instead he throws a huge bankroll at her without even discussing a repayment plan.
Rubbish, I stick to a strict budget but still have the money to lend to close friends. Like Penny is to him.
He might have different budgets for different things. People could get a higher margin because they could be of more use to the scientific mind of Sheldon.