Hi Cloudship,
There is a fairly extensive discussion of boxsprings vs rigid foundations and the types of mattresses that are most appropriate to each in post #2 here.
There are quite a few factory direct manufacturers in the general MA area and the Boston list of them is in post #2 here and the south central MA list is in post #4 here. There are also links to various threads with feedback about many of them in post #2 here.
I also know that most of them including Worley, The Mattress Maker, Gardner, Mystic, FactoryDirectMa (on request but not standard), Sigma, and Yankee mattress all still make “active” box springs for their mattresses that are designed for them (usually but not always innerspring mattresses).
There are still quite a few local factory direct manufacturers all around the country quietly making high quality and value mattresses that are “against the grain” of the major brands and chain stores who are mostly focused on “de-specing” the products that they make or sell to improve profit margins at the cost of quality and using “stories” and massive advertising to sell them. It’s just a matter of finding them and ignoring all the “noise” :).
Phoenix