There was a direct invoicing program (see Temporary Invoicing for Gum’s Med Fields for that background). As you can see, that thread has been closed because that invoicing program has officially been closed.
A few forum friends have since reported that they were able to purchase, even though the program has officially been closed.
tl;dr: The intention seems to be not do direct purchases/invoicing. You can take your shot and see what you get, keeping in mind that we’re on the eve of a holiday. So, you might want to be patient in waiting for a reply for the favor you’re asking.