Customs officers do have a pretty good idea of what items are worth. Because they will check craigslist, e-Bay and even call dealers to establish a value.
If they are suspicious of a deflated price. They will arbitrarily assess a value. They will levy a penalty equal to taxes being evaded on top of fines. Seize vehicles that are being used to import the items. After they have collected the taxes, fines and seized vehicles; they will declare you inadmissible, deny you entry and ban you from returning to Canada. Customs has absolute powers. Their powers of search & seizure, and civil forfeiture are absolute.
Now, is any of that worth trying to save someone else money? My motto is never lie to the Taxman. Not worth the aggravation.