Tasting Beer by Randy Mosher is recommending by the BJCP as a good resource. From a strictly BJCP perspective, the style guidelines have commercial examples which will typify a style. Also, there is a regular feature in Zymurgy called "Commercial Calibration" where 4 higher ranked judges will score a commercial beer BJCP-style which if you can find it in your locale, you could use as a baseline for that sort of thing.