Hi Jbthompson,
There is more about the most important parts of the value of a mattress purchase in post #13 here that can help you make more meaningful comparisons between mattresses.
Based on the commodity cost of the materials inside them … most mattresses made by the same manufacturer and sold at the same retailer would have a similar profit margin and be in a fairly similar “relative” value range (again based only on the cost of the materials inside them) so from this perspective either one would probably be “worth it”.
Having said that … the cost of the materials inside a mattress has very little to do with PPP (Posture and alignment, Pressure relief, and Personal preferences) and how well you will sleep on a mattress which is the most important part of its value.
The only way to know which mattress would be a better match or your body type, sleeping positions, and personal preferences and which one you would sleep best on would be based either on your own personal experience or based on a more detailed conversation with a knowledgeable and experienced online retailer (see mattress firmness/comfort levels in post #2 here). Unfortunately the customer service reps at Costco know very little about their mattresses and aren’t a good source for this type of guidance (see post #4 here about buying a mattress from Costco).
After PPP … the next most important part of the “value” of a mattress purchase is the quality and durability of the materials inside it which is the biggest part that determines how long you will keep sleeping sleep well on a mattress. Unfortunately … both of these mattresses have 3" of 3 lb memory foam in the top layer which would be a weak link in both of them in terms of durability (see the foam quality guidelines here) so I personally wouldn’t consider either of them.
There are certainly better options available in a similar budget range that use higher quality and more durable materials in the upper layers which I would consider to be better quality/value choices than either of these mattresses.
Phoenix