Hi asdox,
This is a combination that many people like because it has a combination of the fast response feel of latex that is modified by the slower response and “sinking in feel” of memory foam underneath it (see post #18 here and post #15 here and posts #21 and #22 here for a few examples). In memory foam/latex combinations I personally like the feel of having latex on top of memory foam because I like a more resilient sleeping surface with less motion restriction with some of the slower sinking in feel of memory foam underneath it but others prefer the “feel” and lower resilience of having the memory foam on top. Of course there are many variations of this type of mattress with different layer thicknesses, types of memory foam and latex, and ILD’s of latex but in very general terms it has some of the “feel” of both materials that some people like a lot. The cost difference would depend on the type of latex but in very general terms latex tends to be more costly than memory foam.
Phoenix