I'm honestly not sure. All you'd pay me up-front would be the $16.99 per card (plus taxes if they charge me taxes). Then you'd pay to have the card(s) shipped to me. I'll cover shipping from me to PSA for everything. Once I get all the cards back, I'd build a package and invoice everyone on the exact amount of shipping for each package back to you. I'd prefer to send everything back to everyone in a priority flat-rate box, but I'd be happy to ship however y'all wanted if you're looking to save money. So, really, it could be anywhere from $5 for a standard bubble mailer up to something like $25 for a large flat-rate box, depending on the number of cards you have graded.
As I said, I'm not looking to make a penny out of this deal. Just trying to grade some cards myself, and save some money while doing it. I figured if everyone else had some cards to grade, this might could save us all a bit of money.