Personally, I'ld just suck up the $35, get my stuff and get on with my life (as many have said).. Maybe fuss to accounting afterwards and see if I can't get it back. But...
If they have already rooted your box as you originally said, why are they still asking for your root password???
If you don't want to give them the current root password and change it afterwards for some reason, why do you not just tell them to boot into single user mode or from removable media and set the root password to something else or nothing at all, and then let you back in when they are done? Do you expect them to insert a backdoor or something? Why would they? They can obviously already root your box.