Since Logitech has stopped developing the Slimserver/Logitech Media Server/Squeezeserver/Squeezebox line of media players, those that remain in the channel are screaming bargains. You'll need an NAS with enough processing power (see Vortexbox/Small Green Computer). But the Logitch Touch and the Logitech Transporter can do an outstanding job of serving hi-rez music for very little money these days.
If you're into DIY audio, check the Computer Audio website for their choices (when they're not gushing about Auralita's etc.). Some solid choices there with long-term viability -- although obsolescence (sp) is guaranteed with any digital source. It's a moving target.