You can still buy new, still shrinkwrapped, recent production floppy disks and new drives. I'd imagine if you're supplying parts for these, a warehouse with a stack of known-to-work floppy disk drives isn't much of an expense and certainly not difficult.
Even if it became a problem, you reasonably have the margins to ask a manufacturer to setup an assembly line and run a new batch just for you - the only downside is that you're likely spending a lot of warehouse space to house the new parts.
