Hi coolgod,
Welcome to the Mattress Forum! 
I’m glad that you’ve found us.
I’m not sure of the exact area where you are at, but you can perform a forum search for a specific town and see what businesses have been discussed here on the forum previously. The southern area of Ontario was also previously mentioned here. If you’re in Windsor, you may even consider visiting the Detroit-metro region.
I don’t actually have a list of all manufacturers or online stores that ship across Canada but here are few site members that do:
Canadian site member manufacturers or retailers …
Memory Foam Comfort
The Mattress and Sleep Company
US site member manufacturers and retailers that ship to Canada across the border …
www.rockymountainmattress.com/
A mattress using all-latex or a polyfoam support core with latex on top could be an alternative for you. This would be more buoyant feeling than memory foam.
Of course, spending more time on a product will be much different than testing in a showroom, but latex does not get softer with body heat, so the feel of the product you would have tested in a showroom would be consistent with how it would feel in the middle of the night.
A latex support core is more durable, more resilient, more elastic, more adaptable to different weights and shapes and sleeping positions, more supportive (it has a higher compression modulus so it gets firmer faster with compression), more “natural”, and has a different more “springy” and responsive feel than polyfoam. It is a higher performance material. Of course, it is also more expensive than a polyfoam core and for some people … a latex hybrid which has the benefits and “feel” of latex in the upper layers (the top 3" - 6" which are the most subject to wear and tear and contribute more to the overall “feel” of a mattress) is worth the cost tradeoff. For others, it isn’t.
I’m not sure where you had read that, but it would be incorrect. Latex, specifically Talalay latex, is generally the most breathable of all foams, followed by polyfoam and then memory foam. All foams are insulators to some degree, and a mattress that is very plush can tend to feel warmer than one that is firm, as you would be “in” the plush mattress more and “on” the firm one more, exposing less of your surface area for heat exchange on the plush model. An all-foam mattress can also tend to be less breathable than one that has an innerspring support core.
There are many variables that can affect the sleeping temperature of a mattress or sleeping system and post #2 here can help you choose the types of materials and components that are most likely to keep you in a comfortable temperature range.
Phoenix