Hi thatsdopefoo,
The first place I would start your mattress research is the mattress shopping tutorial here which has all the basic information, steps, and guidelines that you will need to make the best possible choices in any budget range … and know how and why to avoid the worst ones.
You can read a little more about SilverRest in post #4 here and a forum search on Silverrest (you can just click the link) will bring up more information about them as well.
I would be very cautious here because the specs they list on the Amazon site don’t match their shipping weight (similar to some of the other comments I linked) and it’s very likely that the quality of the memory foam is lower than what they are listing. In a queen size … if the top 3" of memory foam was really 5.3 lb density then the top layer alone would weigh about 44 lbs and since the mattress is listed as weighing 70 lbs that means the 7" support core would weight less than 25 lbs (after taking the cover into account) and this would mean that the density of the support core would only be 1.2 lbs. It’s much more likely that the memory foam is lower density than they are listing.
The tutorial post also includes several links to some of the better online options I’m aware of (in the optional online step) and they include some much less risky and better quality value options that I would consider.
Post #4 here includes some of the better lower budget memory foam, polyfoam, and innerspring mattresses I’m aware of that would be well worth considering and posts #3 and #4 here also include some of the better quality and lower budget latex and latex hybrid options as well.
Phoenix