Hi emdevries,
Welcome to the Mattress Forum! 
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 ā¦ some options or possibilities Iām aware of in and around the Washington, DC area (which has some overlap with the Baltimore list) are listed in post #2 here, and Baltimore in post #2 here.
If you decide to look online, you may wish to use 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 latex and hybrid 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.
Phoenix