I was just at Artisan homebrew in Downingtown two days ago.....didn't see any on the shelves, but I wasn't looking for them. Phone is 610-873-4677. Mike's a pretty serious All Grain guy, so he might have one.
Try Keystone Homebrew in Montgomeryville--kind of a pain for you to get to, but I would think that they would have one in stock.
Home Sweet Homebrew was always a low-tech shop (I bought my starter kit from them back in the late 80s.)--I would be surprised if they carried Marches, but it's worth a shot.
I have heard that Lancaster Homebrew is pretty well stocked but have never been there. Problem is, driving to the tourist trap center of PA Dutch Country on a nice spring weekend is a sure recipe for road rage.
Primary 1: Empty
Primary 2: Empty
Keg 1: Rye IPA
Keg 2: Rye IPA
Keg 3: Chocolate Oatmeal Stout
Keg 4: Empty
On Deck: Lemon Line Hefe, Saison, SNPA Clone
"You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer." -- Frank Zappa