Cost of DIY hardware design: 0 Cost of PCBA from China: rougly 100 to 2000 USD depending on complexity and nr of runs. Cost of DIY firmware and software: 0
Cost of external certification/compliance tests: 5000 to 25000 USD depending on the amount of runs it take to make it pass and what needs to be checked and what the industry is (battery management safety, medical, aerospace, FCC and/or CE, RED and/or others, etc).
So yeah, an RnD department wouldn't really care, but "guy in mom's basement" would.