Usually, high rated users are quite reliable. Though you may want to check to be sure that they got their high rating for selling goods, and not just buying them.
Buying high priced items for me hasn't been a problem. If the turntable was fully manufactured in USA then you won't pay duty, but they will charge GST/PST of the CDN equivalent value +brokerage feels (which are waaay overpriced by UPS). What'll probably hurt you the most is the shipping costs, as turntables are not exactly featherweight.
If you can find something being sold locally, on ebay, it may be better to pay the price if slightly higher, as long as you can arrange to pick up the item.