Are you the DM? Tell them to download some damn PDF's and get over it.

Or find some PHB's at a used book store for around $10, those places usually have no idea how much these things are worth. I just picked up an extra one for $12 in mint condition.

There were obviously enough changes from 3.0 to 3.5 to constitute scrapping an entire line of books less than 3 years later and printing a whole new line. You will never catch all of the changes and you will never actually be playing 3.5.