Well, that fee isn't really a transfer charge, it will add another year to your current registration time (which is normally something you've paid for).
The first thing you are going to encounter is, that DomainZero imposes a 'register lock' on the domains that were registered through them. This is something that should make it interesting to transfer a domain to another registrar. By interesting, I mean theoretically impossible.
I'd like to know what the outcome of this one is, since that 'register lock' in theory, prevents you from doing exactly what you want to do. Whether it can be lifted or not is the concern.
This may end up costing you something. Keep me informated if you would.