I have a couple of 10 count, sealed Sony brand DS/DD 5.25" floppy disks. These are apparently selling on ebay for $10, when they show up. I'll sell them for $7.50/box plus $3.50 to ship within the USA. If you buy two boxes I'll knock the shipping down to $4.50 both.
I also have DS/DD disks of various brands (mostly Maxell) formatted with Apple II DOS 3.3, with a HELLO cataloging/program selecting program on each side, which is also verified with the System Master disk. These I'll sell for $1.25 each. For shipping 5 count or less for $2.50, 10 for $3.50, 20 for $4.50. For more than that PM me and we'll discuss terms for reduced shipping.
The open but tested/formatted disks cost more because of the processing time involved. I will ship overseas, but the hassle factor (shipping documentation) and the shipping cost goes up, so I'll charge a handling fee of $1 more per shipped package. PM me if interested