Hi Barb,
The problem with the Genius is that the firm poplyfoam layer below the memory foam in the Genius that gives it its firm feel is very low density/quality and subject to softening so it may not maintain its firmness or feel over time (see post #11 here).
I would also consider lowering your price somewhat because there are many new memory foam mattresses that have 3" of 4 lb memory foam over a polyfoam base layer (like the iComfort) that are in the same price range as what you are selling this for. The original price of the iComfort mattresses are not good value compared to other mattresses that use similar or better quality materials and designs so $1200 may not be a particularly good deal compared to other similar new mattresses that the people on this forum have access to. You can see some examples in the list of online memory foam mattresses in post #12 here (just look for memory foam mattresses that use 3" of 4 lb memory foam over a polyfoam base layer).
This is not to discourage you from selling it but to make sure that anyone that is considering it can make some “apples to apples” comparisons with other mattresses that are as good or better in terms of quality and have a lower price new than what you are asking for the Genius.
Phoenix