I am on the other side of the country, I use Raintree for most so far.
You could check out Fedco, they have a tree section, they are in Maine. I use them for most seeds.
If you google around for specific varieties you would like you might find sources that way. There is a site called Orange Pippin that is a database of apple varieties, can't remember if they have nurseries listed too.
I just found a nursery in Michigan, Southmeadow Fruit Gardens, Michale Pollan mentioned them someplace, haven't ordered, but their selection is amazing of old and rare apples.
Things like Juneberry are hardy even purchased from a warmer climate. Raintree has some I think. I am in zone 5 and have not had trouble with their stock unless it is a borderline hardy species anyway.