Best place to buy used ds?

Node Nano is probably the best bang for your buck to get you started.  Rated outstanding.

https://www.youtube.com/watch?v=H9tpfdRlHlA

If you have more money to spend, go with Node Icon.  More inputs and outputs including XLR.  Better performer incl. wider soundstage.  Rated highly by TAS, comparable to a $35k combo of streamer / DAC.

https://www.youtube.com/watch?v=qQ57f_AzKd0&t=229s

There are many free, useful reviews available, put together by a few trustworthy individuals. Take advantage of those instead of relying on ad-hoc recommendations from AGers here who haven’t owned or auditioned the gears.

Check out your local thrift stores for used CD's/DVD's! Mine sells them 3 for $5.

Thanks lanx!

It's Time.

Discogs and eBay.

For “Starter” streaming you might also consider the WiiM Ultra. It does a fine job and the App you use to manage it all is very easy to navigate. However, to best inform you it would be good to know the rest of your system..Good luck!  There is an entire world of musical available to you once you start the streaming process, assuming you enjoy it. 😎