Just got to say that I can't believe anyone had the nerve to charge you that much for theophylline. 1800petmeds.com has it for 31 cents per pill.
Theophylline: Heart Medication Tablet For Dogs & Cats - 1800PetMeds
ETA: Scratch that- that's the extended release tabs which should never be split in to separate doses. Doing so can result in an over dose of the medication.
I am surprised that CVS didn't have it in stock.