If you don't know what that is, let me ask you this: Have you seen any hard-skinned squash in an unusual color or shape and can't identify it? That is what we are looking for.
Some great heirloom squashes: Queensland Blue, Moranga Pumpkins, Blue Hubbard
Please suggest supermarkets, grocery stores, big box, corner stores where you have seen a squash. Posting a photo of the fruit and tagging the name of the store (and location) is the fastest way to do this.
More examples of heirloom winter squash and more are here: Pumpkin and Winter Squash Variety Guide
Answer: We went to every fresh fruit market we could from Bloor to Queen to find a source of heirloom squash. Here are the results as of December 1, 2017:
Best selection: The store was in Kensington (Kensington Ave & St Andrew St). There was ambercup, delicata, butterkin, a sweet meat type and more. Squash were offered cut into quarter pieces priced $0.50 - $1, or as whole squash. These varieties were small, 1-3 lbs. There was a long neck butternut and kabocha that were larger (4-5 lbs).
Biggest pumpkin: Corner of Baldwin & Kensington. Huge fairytale pumpkins 15-30 lbs for around $0.80 / lb. This store also sold common squash in small sizes: spaghetti, buttercup.
At most stores, Musquee de Provence (fairytale) pumpkin was found cut into pieces for sale.
Best deal: Lucky Moose mart on Dundas & Beverley. Butternut going for $0.49 / lb, buttercup for $0.79 / lb. Mostly 4 lbs squashes. Some large buttercup on reduced sale cut open for $1.50 each.
Note: When we say "buttercup" we actually are talking about a variety more similar to kabocha, but is commonly known as buttercup. See the difference here: Kabocha vs Buttercup Kabocha vs Buttercup