Hey, Jim,We bought a memory foam (Temper-Pedic knockoff) complete bed, and the 'box spring' is just a platform to make the bed the proper height. So whether or not you need a box spring would depend on the construction of the mattress.
I didn't know they even made box springs anymore. I haven't bought a mattress that needed one in over 10 years, and haven't even been offered one that required one. It was my understanding that the new (new as in the the past 10 years) mattresses had the springs/frame built in them. None of the beds in our house have box springs, and you can no longer flip the mattress because the bottom side is framed in wood with the springs inside. You just set the mattress on a platform.
Where have you found mattresses/box spring combos?