Hi Enzy,
Subject to first confirming that any retailer or manufacturer on the list that you wish to visit is completely transparent and to making sure that any mattress you are considering meets the quality/value guidelines I linked in my previous reply … the better options or possibilities I’m aware of in and around the GTA area (which includes Mississauga) are listed in post #1 here.
A forum search on Mississauga (you can just click the link) will also bring up some comments and feedback from other forum members in the area as well.
Phoenix