5x the cost to manufacture, which would not include product development, not to mention sales, failed products, cost of returns or fixing defects, office rent, testing, certification, support, and on and on and on.

There is a market opportunity and many people capitalize on it. Amazon is full of things like this. Generic items or barely designed items with your brand stuck on them, built by somebody found on Alibaba and shipped to the consumer. They're fantastically cheap, the margins are much thinner, and the products range from adequate to terrible.

It's terribly difficult to build a high quality product people will want for many years (no new design costs) which you don't have to market or do anything with and can just manufacture and sell for a tiny profit. When it is done you'll usually find it as a small very specialized family type business which hasn't sold out yet.