I have tried asking exactly that, sending drive in... Couple of months ago when I called in. I do not believe they will do it in such manner. That would mean keeping track & responsibility of other peoples property.
I see only 2 better alternatives.

1) have the update packages "downloadable" and make it $75 cheaper than sending physical drive.
2) send update (just update) on usb flash drive, which would cost a bit cheaper than spinning hard drive, cheaper to send, easier to store. Reusable.