Hi Thatg,
You can read a little more about bedinabox in post #2 here.
There is also more about why I would be very cautious using reviews as a way to choose a mattress in post #13 here and post #4 here.
I would be cautious about buying a mattress that used 3 lb memory foam unless you were in the very lowest budget ranges.
If you follow the steps in the tutorial post one by one you will have much higher odds of making a great quality/value choice.
Phoenix