Defective fan.... what should i do?

Im not sure if this belongs here.

I purchased two zalman ZM-F3 fans from performance-PCS and while one of the fans is very quiet even at full speed the other identical fan makes a loud clicking/humming noise... I have taken both fans off my Mugen 2 to make sure it was the fan all by itself making all the noise and not because of its location in my case sure enough one is quiet while the other sounds like a completely different annoying fan.

So i emailed performance PCS about the defective fan and they want me to pay return shipping and THEN decide for themselves if its truly "defective". The fan still works so i am a little worried about spending the $5 shipping on a $10 fan to ship it back just to have them consider it not defective and ask me to pay MORE shipping to return it.....

So, what should i do?

1. Pay the $5 shipping on the $10 fan and hope they consider it defective.

2. Don't bother and consider it a waste of time and $10 + the shipping i already paid.