Brambleberry averages .50 to .36 per box depending on quantity, but I like their boxes a LOT. Similar looking to those, but with an oval window, crisp edges, thin cardboard, nice and neat looking. AND, rather than being a single box, they're a tray and sleeve design, which I just love, because you can slide the soap out without touching it, to see the whole soap, and you can also wrap the tray in cellophane and then slide it into the sleeve, for a more professional look.
The ones you posted are simple boxes, looks to be the same nice cardboard, but they just have flaps at either end, not a tray and sleeve.
Wholesale Supplies plus has similar boxes, but the oval window is right in the middle, leaving no room for a label on the front, which may be fine depending on your labeling. they average between .27 and .36 depending on quantity. Same nice cardboard. Simple box, no tray and sleeve. They also have one with an offset rectangle window, or ones with no window at all.
THIS company, has a variety of different designs of soap boxes. I ordered from them a few months ago. They are sized well for larger bars of soap, and would be good if you were packing them for shipping, as the cardboard is thicker corrugated cardboard, rather than the thin cardboard like the others. That being said, I personally don't like them as well. They're not as "crisp" and "neat" looking, I have to pick the cardboard fuzzies off the edges when I put them together, the trays just don't slide as nice. They just feel clunky to me, after having used BB's. But they are about .33 per box, and like I mentioned, many styles to choose from, and good for larger soaps.
There's more out there... try searching "Candle and Soap Boxes" on google.