I really don't think there is such a store in all of New England.
Believe it or not Guitar Center probably still has the best selection of basses I have ever seen around here. Before them, I would drive from store to store (still do/would) to try out different basses.
You can definitely try out Pedulla, Warwick, EBMM and Fender at GC, although Pedulla may depend on the store. The one in South Attleboro usually has a couple different models.
I did see a used Metro at GC once. Poor thing had some problems. Other than that I have never seen a Sadowsky outside the internet or at a GTG. I think there are only a few stores that stock Metros and none of them are around here. Most come straight from the Sadowsky store. A new Metro will be above your budget. If you get a chance to try one and like it they pop up often in the classifieds here.
Try out Alpha Audio Works in Mystic Connecticut.
http://www.alphaaudioworks.com/Category.aspx?id=2
I bought a Lakland 55-94 from them back in 2000. Looks like they now carry a few more brands in the mid to high price range as well as MM and G&L. Unfortunately their website does not show actual stock though.
It's really worth checking out your local music stores. The selection may be smaller, but they all seem to carry at least on brand that may be hard to find elsewhere. You just have to put a few miles in to find out.
EDIT:
Also check out Boston Guitar Works: (actually in Brockton)
http://www.bostonguitar.com/Merchant...gory_Code=06BG
I haven't been there, but have always wanted to go. They seem to have a good selection.