And I did look into building a batch of these a while back and I don't know how c0pperdragon was hitting that price point!
I estimated like $45/each in parts alone for a batch of 10.
It'd be about $130 in parts for one unit (mainly because the PCBs, stand-offs and screws are only available in bulk, shipping from at least 4ndifferent suppliere, a UPDI programmer... it adds up fast)
I don't want to spend $450 on parts to build my one hot plate and then have 9 extras left over that I have to try to sell.