I believe the K50 list did increase to $17,500. The Antipodes K22, however, also has I2S output and list price for it is $9,000. If interested in Antipodes, you could also consider the S Series, which are separates as opposed to all in one box for server, player, and power supplies.
Are There Roon Ready I2S Streamers?
I thought that it was worth asking.
I'm using an IFi Zen Streamer with USB out to a MacIntosh MA1200, but I'm looking at the Denafrips Terminator Plus R2R DAC and multiple reviews have been less than kind regarding using the USB in. This would mean adding the Denafrips Gia to reclock the USB in and export via I2S directly to the Terminator Plus. I figure that it would be best to just find a good Roon streamer with I2S out.