Increasing speed of python code

I have some python code that has many classes. I used cProfile to find that the total time to run the program is 68 seconds. I found that the following function in a class called Buyers takes about 60 seconds of those 68 seconds. I have to run the program about 100 times, so any increase in speed will help. Can you suggest ways to increase the speed by modifying the code? If you need more information that will help, please let me know.

def qtyDemanded(self, timePd, priceVector):
    '''Returns quantity demanded in period timePd. In addition,
    also updates the list of customers and non-customers.

    Inputs: timePd and priceVector
    Output: count of people for whom priceVector[-1] < utility
    '''

    ## Initialize count of customers to zero
    ## Set self.customers and self.nonCustomers to empty lists
    price = priceVector[-1]
    count = 0
    self.customers = []
    self.nonCustomers = []


    for person in self.people:
        if person.utility >= price:             
            person.customer = 1
            self.customers.append(person)
        else:
            person.customer = 0
            self.nonCustomers.append(person)

    return len(self.customers)

self.people is a list of person objects. Each person has customer and utility as its attributes.

EDIT - responsed added

-------------------------------------

Thanks so much for the suggestions. Here is the response to some questions and suggestions people have kindly made. I have not tried them all, but will try others and write back later.

(1) @amber - the function is accessed 80,000 times.

(2) @gnibbler and others - self.people is a list of Person objects in memory. Not connected to a database.

(3) @Hugh Bothwell

cumtime taken by the original function - 60.8 s (access