In the US, the Ryzen 9 3900X MSRP was $499 but is $70 less now. (Initially, supply was low, and it was selling over MSRP as high as ~$570.)
But they came with coolers... I have a Ryzen 2700X that I got for $230, and I still use the stock cooler. To jump to a Ryzen 5800X plus a cooler would be a huge expense. I will definitely be on the sidelines for the next six months, but then I'll revisit the pricing situation (once motherboard manufacturers release updated 400-series firmware.)