Music playing/streaming options without a computer (squeezebox, WD live, Nexus Q, PlayOn!HD)

I have an external HD full of ~300GB of music, organized via an iTunes library. I want to play the music through my HiFi receiver, but I don't want to spend hundreds of dollars on a new computer.
Can anyone recommend a system I can use, with streaming to other devices as a nice bonus option?

Some options I've considered:

- WD Live TV (I use for my TV set) has a nice USB slot, so I could plug in my hard drive and use the RCA jack to connect to my receiver. But that will have poor audio quality, it'd be a nightmare to organize and add music files using that UI and I don't think I can stream *from* WD Live (though maybe I can - I haven't looked into it).
- Squeezebox, Nexus Q, I don't have the ability to connect my existing music library.
- NAS, would cost >$200, plus I'd have to get some other device anyway, in which case I might as well buy a Mac Mini.
- AC Ryan PlayOn HD mini, looks ideal, except I live in the US.

It looks like ASUS and Masscool make media servers/players, but I don't know a think about them.

So, are there any good ~$100-200 options here?

Thanks for the advice.
I do have about 30,000 tracks, so it's definitely good to know about Squeezebox Touch's limitations.

So it sounds like a computer/server is really the way I'll have to go.

Any suggestions? I'm partial to the Mac OX and would be inclined to get a used mac mini for a couple of hundred dollars. But is there another option I should consider that can stream and run iTunes? Like some UNIX box running PLEX, which I've heard about but I've never used?

Thanks kindly.