Hi diamondshopper,
Thank you for the post and for your update. I am happy that the information on our site was assistive to your successful DIY and additional mattress purchase. Just for your information, the @Crank posted in 2013, so I am not sure you can expect a response, many consumers find the information they need and move on with their purchase decision.
In early 2018 we decided to discontinue the provision of listings of potential retailers in various geographic regions (unless they are already approved site members), because of the difficulty in maintaining such lists in a retail landscape that is constantly changing, and most importantly the confusion it was created with the consumer members who incorrectly assumed that these businesses had indeed gone through the strict qualification process and were approved as members of The Mattress Underground. Such an assumption is unfair to both the consumers seeking assistance, as well as the very businesses and manufacturers who meet the criteria to become Trusted Members of The Mattress Underground.
Regarding the pricing of a retail bed, it’s difficult to comment on a specific bed, especially when we do not have complete specifications. As you compare beds from people that are transparent about the materials, you will be able to see the value equation. I’d also keep in mind that retail prices in Canada, and sometimes in bigger cities, and different promotional periods can influence retail prices. Generally speaking a 13" mattress with a 2.8lb Qualux foam from Carpenter, with 5" of latex can get quite expensive.
I understand your points about the DIY covers and having less choice in Canada. You most likely are familiar with this this post. While not inclusive, there are some component supplier options listed here, with a few Canadian sources here. You can reach out to MFC, who have great experience in this area and are trusted members of our site with 30 years of experience in foam and latex foam. Dormio as well … is a trusted member (and geographically closer to your location) that you may wish to consult, both are expert members on the site and would be happy to assist you in any way.
Thank you for the kind words about TMU, it is always nice to hear 
I look forward to your further updates and findings when you have a chance.
Phoenix