I don't think so. I don't know where people get these ideas and/or made up rules from. Price has nothing to do with whether you can import something and a stock is no different than buying a scope from the states. I've bought several scopes, reloading tooling and supplies, and a stock from vendors in the states. Some things from ebay, the stock was from the factory (ATI pistol grip 10/22 stock). I've brought back (in person) 5000 bullets and 2000 primers and no one batted an eye. The biggest reason a lot of shops won't ship to Canada is because they are scared sh*tless of the ATF. They don't know and won't find out the exact rules so it's easier for them to say no. There are lots of shops that know what is going on and will sell to Canadians. You likely won't get a receiver or barrel, but springs, firing pins, etc. can be found. Start googling what you want and start making phone calls. The stuff is available. There is no duty or brokerage fees unless you're stupid enough to use UPS. At worst your going to pay shipping and GST which you're going to pay anyways buying in Canada, if you can find it in Canada.
There are so many Chicken Littles on this forum that think a US swat team is going to come storming through their door some night for buying a 70 dollar Bushnell scope online. Do anyone really think the US gov. gives a sh*t about a 70 dollar scope that is readily available here anyways? I think not. A fancy themal imaging scope is likely a different story.
Just my 2 cents...