Forum Post: Expense Slips - entering Price and Quantity

I am trying to enter Price and Quantity in Expense Slips.  For example, there were 20 copies made for a particular client.  We charge that client .10 cents per copy.  Some clients we charge .20 cents per page.  So, since the parameters are different depending on who the client is, does that particular information have to be entered somewhere else before I actually type in the expense slip?  The defaults for Quantity and Price don't make sense.