try seeds of diversity if they don't have it they'll probably know who does.
they have a resource list of canadian seed companys that stock rare seeds.

Here is a link that might be useful: seeds of diversity

Hi pocketsquirrel,

You may find that these wont grow in our area. Here is a document for you to read ( its short) that talks about why the potato onion is grown in the south and not here in Canada .

http://www.eap.mcgill.ca/MagRack/COG/COG_A_96_08.htm

Also if you decide you would still like to search these out you could search for "hill onion" or "Yellow multiplier" onion

Signet