Are you looking for a device that is "Roon Ready" and has a built in renderer/player or are you looking for a device that is compatible with a Roon Server/Renderer like the Nucleus or a Nuc connected via USB? The list of DACs with a bridge to handle Roon directly is not that long. You probably would be better looking at a streamer/player with a built in DAC like Naim, Lumin, Aurender, Auralic, etc...
If you are looking just for a USB DAC that will interface with a Roon server/player, I would check out the Rockna Wavelight. A hair below your budget, but is a really awesome R2R DAC with an FPGA interface.
If you are looking just for a USB DAC that will interface with a Roon server/player, I would check out the Rockna Wavelight. A hair below your budget, but is a really awesome R2R DAC with an FPGA interface.