How do you ship these?
In a round box.
I got some fairly strong ones which are disks, slightly smaller than a silver dollar. They shipped them in a box about 4 inches four inches by six inches. Each magnet was wrapped inside a corrugated cardboard strip rolled up so there were about six layers of cardboard around each one, more than an inch on each side. They will stick together even with that much cardboard between them. Put one [still wrapped in cardboard] in a little paperclip tray and it will suck up all the paper clips.
One problem with them is they are really fragile. If one smashes into another, they can break and pieces can go flying, and will stick to any metal they encounter.
You can get them rubber coated which reduces this risk.
They are really nasty.