Shipping speakers

Not the most economical, however I have used them twice, no problems.

https://www.cratersandfreighters.com/

And....don't forget, even if the buyer doesn't mention it, the shipment needs to be insured....."just in case"

I would think it would be just as cheap to rent a U Haul and drive them to the destination if you consider shipping and insurance charges from a third party. I figure it couldn't be much more than 400 miles from MD to RI but I've never been to either state. At 200 miles an hour it would only take a couple of hours to get there.