Gabe invested $350 in baseball cards. If he lost d dollars when he sold the cards, which expression represents the amount of money he received for his baseball cards?

A. 350d

B. d - 350

C. 350 - d

D. d + 350

The amount of money Gabe received for his baseball cards is $350 minus the amount he lost. To represent this mathematically, we can use the expression 350 - d. Therefore, the correct answer is $\boxed{\textbf{(C)}\ 350 - d}$.