....need floppy drive for FD-88---
Try eBay.  I've see quite a few 'as is' sales on early Mavicas, FD-73,
81, 88, etc.  Also look for a camera repair shop that works on digital
stuff, they may have one that can be cannibalized.  Worst case, again
eBay:  buy another one.  I'm hanging on to my FD-81 because I couldn't
get enough selling it to make it worthwhile.  I leave the FD-81 in my
Westy (Vanagon content) as a backup and for spur of the moment stuff.