Hi kromix,
Welcome to the Mattress Forum!
If you’re interested, there are some comments about the Loom & Leaf in post #5 here and a forum search on Loom Leaf (you can just click the link) will also bring up more comments and feedback about it as well.
Loom and Leaf (from Saatva) only sells their products online direct to the consumer, and they would have absolutely no affiliation with the place you mentioned. So anything found outside of their web site certainly would be from some sort of a “reseller”. You are correct that this means it would not come with a manufacturer’s warranty, and would most likely be a comfort exchange or defective/damaged/warranty return product that is commonly sold to “liquidators”, "resellers, “closeout centers”, and “clearance stores”. Here’s a video describing these “closeout centers”.
There is more information about some of the things you can check for if you are considering buying a used mattress in post #2 here and if you are considering buying a mattress from a liquidator or clearance store that sells used or returned mattresses without a warranty then there is more here and here and here that I would read before considering your purchase. While the “value” of any purchase is something only you can determine for yourself, I personally don’t find much of a value in a product, regardless of the discount, where you have no assurances of what the product has been through or how it has been used, and you have no guarantee of the “chain of command” of the product since it was produced. Personally, I would be very cautious about buying a mattress such as this from a place such as the one you mentioned. I would consider it to be a “buyer beware” purchase (see post #8 here).
(Additionally, I removed the link in your initial post. While I’m assuming you’re simply asking the question about buying mattresses from unauthorized retailers and not affiliated with that site in any manner, simply having the link in your post provides a “promotion” for the site in question.)
Good question! I hope my answer helps you make up your mind as to how to proceed. B)
Phoenix