IMO .biz is not worth it unless: a. keyword is top-notch and b. you are willing to wait for a few years for .biz to increase in value (I doubt it but who knows).
I prefer the .us version. The .us has been gaining momentum but has yet to mature.
I believe Shopmusic.us is good, and now is the time to fetch remaining available.us names.
IMO fast forward 2-3 years the TLD will be more accepted.
it's a nice domain, but I'd be truely shocked if you were to get more than low XXX for it. That's just my opinion though, I've been wrong b4 and I'll be wrong again soon.
Where did you get that kind of appraisal ?
The name is good but you've got to be realistic. Very few .us names have sold for $xxxxx to date, and the ones that sold were premium keywords like business or food.
Your name is nice but not truly premium IMHO. But I think time is on your side and .us names may increase in value over time.