You know what would be an interesting venture? Setting up a company to grow exclusively the bittersharp apple varieties...foxwhelp, kingston black, and others...and then juicing them, and pasteurizing them to the point of shelf stability and bottling in plastic 1gal jugs. Then sell through brewing supply channels.
I have no idea if they sell 'sweet' cider or apples or what but this place looks pretty cool for you new englanders
I saw an interview with the guy who started this orchard in Michael Pollen's Botany of Desire
Poverty Lane/Farnum Hill does
grow and sell cider apples and other heritage varieties of apples. They will also sell cider stock for fermenting in the fall. Just bring your carboy(s) and they will fill it. Last I checked it is about $8 a gallon. Not much help to you in WI, but ask around. You may find a source out there. You can buy apples direct from them online I believe. They also supply regional grocery stores with some varieties. Less so of the cider apples at stores. Steve Wood the owner is a pretty nice guy. Knows his apples!
You can make decent cider with common eating apple varieties, but if you want the good stuff you need at least some bittersweet/sharp varieties in the mix. I have made loads of cider from apples growing unnattended. Many abandoned orchards up here in VT. They are ususally pretty acidic though.
I will bet you can find some orchards over there which grow some cider varieties. They will likely be English/French varieties but grown there in WI. You do not need large amounts, in fact it can become unpalatable if you put too many of certain
bittersharp varieties. There are only a few that will make good "singe varietal" ciders. Use more familiar apples such as Liberty for the base cider and then "spice" it with some cider apples like Kingston Black, Harry Masters Jersey, or Somerset Redstreak. If you cannot find anyone growing any cider varieties (though I bet you will if you ask around) then you can add very small amounts of crab apples to get some of the tannins and acidity. Be careful though. These can over power quickly!
If you do want to grow your own or just read about some cider apple varieties check these folks out.http://www.cumminsnursery.com/cidervar.htm
Get out and start talking to the orchardists. If you show some knowledge and interest I am sure they will be happy to talk apples with you and point you in the right direction! Sharing some of your cider efforts can't hurt either!