VingtTrois, that's very kind of you but I actually have plenty of floppy disks, I was lucky that the electronics shop across the road was getting rid of boxes of 25 and 10 disks for $1 per box, so I grabbed a bunch, went back a week later and they said no one else had bought any so I picked up the rest. I just can't afford postage for them at the moment, I spent my rent money on Halloween props and decorations :p
But for others I think we should clear up the Double-Density/High-Density issue. Amiga Technologies A1200s (not Commodore A1200s) have modified high density PC floppy drives in them, and so they can't read HD disks formatted as DD unless you put a small piece of tape over the extra hole on the disk. Some A4000s with Amiga HD drives might also require the tape over the hole of a DD-formatted HD disk, but they can also read true HD disks formatted in 1.44MB DOS or 1.76MB Amiga format. Amiga 500s and 500+ computers all came with Amiga DD drives, and so they have no idea what a HD disk is anyway, and simply recognize every disk as DD.
However, a Double-Density-formatted High-Density disk is more susceptible to data integrity issues and can develop read errors over time, sometimes even after a few uses. These errors don't seem to be physical, so the disks themselves aren't damaged once the errors develop and you can usually rewrite the disk back from the ADF or DMS image and it will work fine again for a while. Some people say that if you write the image to the disk twice or three times first it stays on there longer. I don't know if it's true, but I do this anyway just to be safe.
I would recommend anyone who is sending out Amiga disks on HD floppies to send two copies of each one, just in case one develops an error and is useless to the recipient.