I use Advantix II on the pups, and previously had been buying it thru a supply house in Australia at a very good price. However, I found it cheaper this year from Foster & Smith. I get the 12 dose package for 11-20 pound dogs, and it was $117 on line - even cheaper than what they had advertised in their catalog. Of course after I ordered it I found it at Petco for $107. Just my luck! I don't know why anyone buys thru 1-800 Pet Meds - they are expensive on everything!!!! Guess people fall for the t.v. ads and don't do their homework and comparison shop.