Why do they seem illegitimate? Looks like 100s of other online music suppliers, like a couple here in Denver, both of which I have done business with and can recommend:
Honestly, probably fine to deal with. Their feedback is low because they don't have a lot of recent feedback, but their account stats show over 20K items sold, so they would have been pulled from eBay if they weren't fulfilling orders or received too many complaints.