I understand all that, but it still ain't worth $40. And you have to pay the shipping cost, putting 2 in same box doesn't cost them anymore.It's a low volume item. Imagine the time and effort in design and prototyping to get the functionality right. And then you have to sell it, which means marketing cost, packaging, taxes, banking fees, credit card fees, covering shipping for two or more (have you seen shipping rates lately?). Material and machining costs are probably the least expensive element of that business.
Rosewood