Hi stpfun,
You’re sure not having much luck with retailers being in stock!
Did you order the Seven Comforts topper from their Amazon site or from their own site? If you ordered them from their own site here (which lists the king size at a little higher price) and they refunded you then I’m guessing they are either out of them or don’t make them any more. They are not great at customer communication and they have never answered several emails I sent them … although I do like their product.
There are some good latex (and other) topper options linked in post #4 here which may work well for you if your mattress is too firm and still in good condition. I would tend towards being conservative in terms of thickness (2" or less) if you have a Posturepedic because it will have several layers of soft polyfoam in the comfort layers already.
One of our members also sells a similar “lanoodles” latex topper here and while it is very good quality, it is also more costly than the Seven Comforts topper and well above your $200 budget. Another one that is also more costly is here. It may be difficult to find a good quality covered king size topper in this budget range and especially with latex and you may need about another $100 or so to be “in the range”.
Most of the Aerus memory foam toppers are 4 lbs and a quick google search only showed one 5 lb Aerus source but it’s also over your budget.
Overall I would make your choice between the options in the DIY sources post I linked or the links it contains to Cymax, Unbeatable sale, or Sears if you are looking for less expensive memory foam options.
Phoenix