I am posting this as a Comment for several reasons; first, since
Google Answers will be effectively closed forever in approximately 45
minutes from the time of this post, it would not be fair to you to
throw a hurried Answer in at the buzzer, especially since your
Question sat unanswered for a whole month; second, because the answer
will still require work on your part. So, consider this a freebie if
you must, in honour of the demise of Google Answers.
The mats you are looking for, are something that I am very familiar
with as I have had to almost carpet my home with them ever since my
little one became a toddler. They are great for preventing nasty
bruises when a little one takes a tumble! They are known as
interlocking foam tiles, and interlocking anti-fatigue mats.
In the Montreal area, your best chances of finding them are actually
the very same chains that I purchased them at (although I am in BC).
Walmart periodically carries both a four-pack of black interlocking
squares, and a four-pack of red/blue/yellow/green squares. If they are
in stock, the black ones can be found in the Automotive/Hardware
section, while the multi-coloured pack can be almost anywhere: Baby
section, Floor Coverings, feature-aisles. Call up the Walmarts in your
area, and ask for the Automotive section, they are the most likely to
know what you are asking about as these are very popular as
anti-fatigue mats for garages and workshops. The last time I purchased
these, earlier this year, the price was approximately CAD$10/pack.
Home Depot also periodically stocks a multi-coloured four-pack
including finishing edges (little strips that interlock and give a
'clean edge' look), typically in a feature display at the end of an
aisle (in other words, not as a regularly-stocked item). These are
more appropriate for a child's play area due to the colours, and run
approximately CAD$12-13/pack. They are not necessarily compatible with
the Walmart tiles.
Good luck, and best regards,
Google Answers Researcher