Manchester, Nashua, Concord

New Hampshire Store Fixtures
10 Columbia Cir Merrimack, NH 03054
(800) 325-1030

Check craigslist (website) for store fixture liquidations in Manchester, Nashua, Concord and Dover.
Still looking?  Check the major cities out of state for closing stores.
You will find your first (established) used shelving dealers in Boston and New York
Try these nearby states:

Maine

Massachusettes

New York