you pay nothing to send your jewelry to USGB-they reimburse fedex. that line that says they reimburse for shipping is if your jewelry is worth more than $5,000, they recommend you send it USPS certified (or maybe registered?) mail. if you do that, they'll reimburse your USPS shipping costs.
ETA: in the instruction e-mail, it shows a sample airbill so you'll know how to fill out the fedex airbill. it's got the USGB fedex account # on it, and you just put it in the correct blank.