You can add additional features to Regular Parcel and Expedited if you print the label through Canada Post's online Snapship service. Go to canadapost.ca, click the Login Or Register text at the top right corner. The only thing you need to register is an active credit card. While it is aimed at Small Businesses, you do not need a business number to sign up.
When you choose your label, you will see additional add-ons below. Click the box next to signature confirmation.
Additionally, for unique collectibles that cannot be replaced or expensive orders I would recommend selecting the 'card for pickup' feature. Buyers generally don't like this, because it means they have to pick up the item at the post office. Still, it is a good anti-fraud measure. While it doesn't really do much, it might spook someone who intends to scam you. Keep in mind, you STILL need to select the signature option on top of this. Canada Post won't collect a signature by default with card for pickup.
On a side note, I would consider putting the item up as a Buy It Now w/ Best Offer for a period of time before auctioning it. Even if you inflate the price a bit higher than what you expect to get for it, and accept offers, you will likely get more than you would with an auction. Auctions rarely realize or exceed peak values for items. There are a few exceptions, but generally, they are only good for when you want to liquidate stuff and you don't care what you end up getting. This is especially the case if your item is a more niche collectible with a slimmer audience of potential buyers.
