Is it possible to buy potassium bromide on-line for my dog. I am unemployed and the pharmacy charges $75.00 per mo. for the compound formula in beef flavor

Optional Information:
Age: 10; Male; Breed: pitbull/boxer

Already Tried:
He is on phenobarbital 3 sm pills in the morning and 2 small pills at night....He recently had 2 seizures in a 4 hr period. His Phen. level is now 22.2. We just introduced KBr today..22 ml for the 1st 4 days , then 6.5 ml on a continual basis. I have a discount card for his meds., the pheno. costs me about 14.00 per mo. . Since I am unemployed, i can not afford his meds, his KBr is in a compound liquid, so no major pharmacy will do this , and this is those are the only places that take the discount card. I am doing what I can for my dog, I can barely pay my own bills...I have put my dog first many times...I can do without a lot, but not my dog. If you can , please help...XXXXX XXXXXX