Not sure if it meets your geographical criteria but Bass Pro in Foxboro ususally has some. haven't been in there in a month so you should let your fingers do the walkin before heading in that direction
finding Titegroup is like looking for bigfoot...heard its out there but haven't found it yet. I was in Bass Pro the other day and didn't see any and I don't think flint carries a lot of powder. NET usually has a lot of powder if you dare go there.