The site below has some neat small containters for holding items in a first aid kitor PSK, and free shipping with no minimum. Click 'Packing' under the 'gear shop' section of the left frame, and most of the good stuff is under 'storage containers'. They also have good prices on some water purification chems and a few other items.
I particularly like the microdrop bottles($8 for a 3-pack), which are tiny dropper bottles small enough for a PSK and are great for holding water purification chemicals, tea tree oil or other antiseptics, eye drops, soap, etc. They also have nice 2"x3" zip lock bags that are 4 mil thick, very useful for all kinds of small objects.

The site: http://www.backpackinglight.com/

Some pics: