The interweb is full of opinions on which SKS is best. Of the models common in Canada, the best would likely be a Yugoslav M59, then a machined Russian Simonov and the lowest quality would be a Chinese SKS. The first one will be almost impossible to find due to limited imports and ongoing export controls. There are zillions of Russian guns nowadays, and lots of passed over Chinese ones.
Where to buy? Read the little jpeg ads across the top of the main page. There are lots of dealers and plenty of reason to buy local.