Hi layiyiyi,
You’re welcome!
Subject to first confirming that any retailer or manufacturer on the list that you wish to visit is completely transparent (see this article) and to making sure that any mattress you are considering meets the quality/value guidelines here … some better options or possibilities I’m aware of in and around the Washington, DC area (which has some overlap with the Baltimore list) are listed in post #2 here. The mattresses I linked to are mostly online options, so these specific brands aren’t commonly found in showrooms.
While certainly not complete, there is a list of spring/latex mattress (hybrid) providers in post #2 here.
Phoenix