Hi cml1961,
Hopefully you’ve read this already but just in case you haven’t I would start with the mattress shopping tutorial here which has all the basic information, steps, and guidelines you will need to make the best possible choices … and know how and why to avoid the worst ones.
Once you get to step 3 … the better options and possibilities I’m aware of in the Philadelphia region are listed in post #4 here.
Magic Sleeper is certainly one of the better options in the area and I think highly of John Santos the owner.
This article includes the specs that I would make sure are available from any retailer or manufacturer you visit and post #4 here has more about the quality and foam density guidelines I would suggest.
Phoenix