An option is a used Bricasti M3 with built-in renderer. The brand’s products are more obsolete resistant than others. It will require a separate server to run Roon in order to stream. That means there is the cost of Roon plus an inexpensive server, like $1000+. The advantage is the savings on the streamer. The built in renderer sounds good. I hate to be one those buy-what-I-bought, but I do think the built in renderer offers a really good value and certainly doesn’t prevent future upgrades.
I have tried my iMac/audirvana as a server. Even through the network input of my M3, it sounds awful.