Maryland has some obnoxious laws that leave Quest Diagnostics as the only blood lab that works with the companies that allow consumers to order bloodwork. And I only know of two such companies:
At the time of this writing (early 2017), even Life Extension, a company normally willing to send blood draw kits to restricted states, won't ship to Maryland. It might be worth re-checking with them periodically though, because they're often much cheaper than other providers.
If you're near the border of another state, it could be worth doing a price comparison with the providers mentioned on my individual test pages, since many of them only care about the state in which the blood is drawn.
That's all I'm aware of for Maryland. If I've missed anything, please let me know in the comments so I can improve the page.