Scott,
Yes, you will need 3 licenses.
Yes, you can set it all up now and it will work although it is not legal since you don't have the client access licenses.
As for where to buy, check out
www.pricewatch.com. Go to the software section, select operating systems and search for Windows 2003 Cal. this will give you a list of places that sell CAL's. You will need to do a bit of reading/calling them to make sure you are getting exactly what you need.