Are you near a winemaking store? Most sell pH calibration solution. You can order from enartisvinquiry.com and I'm sure Amazon and eBay have it.
Something is always fermenting....
"It's Bahl Hornin'"
Kegged: Sour Saison, Pale Ale, Aggie Ale, Firestone DBA, De Koninck Blonde
Bottled: Belgian Quad (Grand Reserve), Derangement (Belgian Dark Strong)
On Deck: Pliny the Younger