In the US the 1600 is $169 and the motherboards can be as low as $40
The 8400 is $189 and motherboards at best are $100 and not very consistently.
The 1600 is usually 190-210 USD and the B350 boards that are decent for OCing are 85-110+. They are very similar in price . But if you want the full potential from Ryzen you need 2933-3200MHz RAM which is $150+. That's why I went with an 8400 over the 1600. If RAM wasn't so expensive or Ryzen wasn't so dependent on it I would've got a 1600.