Numbers formula question regarding IF equations

[nikkiphish]

Hi there, I am currently in the process of starting my own business. I am using Numbers to create an inventory and I am stuck on a formula. In each row I have a product that I carry, followed by the options available for that item. Example: Business cards, and the next column is quantity with a pop up menu of all the available quantities. The next column needs to reflect the cost of the quantity selected. So if the quantity is 100, the next column needs to show $23, if the quantity is 150, then it would be $31, and so on. I thought I was on to something when I did this: =IF(F3=100, “$23”, “”) and got $23 to show up in the column, but I have no idea how to have several conditions, I keep getting errors. Help here would be GREATLY appreciated!!! Thanks!