To find the total amount of money for a group of people eating at the buffet at Pizza Ranch, you can multiply the cost per person by the total number of people. Since the buffet costs $10.50 per person and \( n \) is the number of people, the expression for the total amount of money is:
\[ 10.50n \]
This expression represents the total cost for \( n \) people eating at the buffet.