Check with @All Things Aquatic in foxboro, maybe Lovely Pets in Kingston. How much are you looking for? I'm in East Bridgewater and can always help out in a bind. I run Brightwell Neo Marine. Usually always have at least 30 gallons of salt and RoDi on hand.
We typically have 1500 gallons of RO on hand and about 300 gallons of salt water at any given time, so unless you catch us in the middle of a big water change, we should be able to help you @ All Things Aquatic in Foxboro