Hi dairymaid,
Subject to first confirming that any retailer or manufacturer on the list you wish to deal with is completely transparent (see this article) and to making sure that any mattress you are considering meets your specific criteria and the quality/value guidelines here … the better options or possibilities I’m aware of in and around the Topsham area (which would include Lebanon and Montpelier) are listed in post #4 here.
The Burlington list is in post #4 here.
Phoenix