Hi Ari,
You could start by looking online and using the experience and expertise of the members listed in post #21 here who are all very experienced and knowledgeable and specialize in providing the type of help and guidance on the phone that can help you make good choices. There are a wide range of memory foam options included in the choices there and I believe that all of them compete well with the best in the industry in terms of their quality, value, service, and transparency.
At a quick glance from that list, for someone in the mid-200 pound range, while not a “traditional” memory foam mattress, SleepEZ offers the substitution of a 3" Sensus 5.5.lb memory foam layer in models with a 3" comfort layer. Rocky Mountain Mattress offers memory foam options, some using higher density foams. Novosbed has one memory foam model using 5 lb memory foam. If you’re in or near Canada, Memory Foam comfort has a wide selection of quality memory foam mattresses, and TMASC features a heavier-duty Natura memory foam mattress.
In addition to the online members of the site listed in the previous membership link, post #12 here has some of the better online memory foam options for those who are looking for a memory foam mattress.
I hope that helps give you a few new options.
Phoenix