Generally you want to charge 4x your BOM (bill of materials) to cover shipping, fulfillment, customer support, etc. For such a small run (50 pieces) your costs

Generally you want to charge 4x your BOM (bill of materials) to cover shipping, fulfillment, customer support, etc. For such a small run (50 pieces) your costs are probably a lot higher than that of a large manufacturer; in their case they'd probably want to do > 4x to actually turn a profit. At $148 I'd be amazed if they were doing more than breaking even – these guys are doing it for the learning experience (and it says so on their blog).