My brother gave me a broken down Cadi STS 2005 with only a door key and no transponder. This is one of those, "if you can fix it, it's yours" kind of deal. I don't really want to dish out $200 to Cadilac for this key just to get the car running, but I'm reading that as long as I have a key I can program any blank transponder to the car. Is this true? I want to believe the following e-how:

http://www.ehow.com/how_7314562_program-remote-sts-cadillac.html

but there are other forums that say if you lost the master key, only a dealership can program. The dealership called this key, "the valet key".
(I'm not sure why it's called a valet key given that this key alone isn't enough to power the vehicle..)

As a student, Cadillac part prices are ridiculously high so obviously I'm trying to cut corners here!

I should add, the main reason I want to avoid the dealer is because I'd be required to get the vehicle to the dealer. Car is broken down, which means I need a tow truck TO and FROM the dealer. $200 + the towing is an expense I'd like to avoid. I intend to fix it myself.

Thanks !