I use Frontline Plus as well. I have been getting it from the vet but, having just picked up a 3 month supply for 4 dogs yesterday, I'm going to search the internet!

Related, what do you use for heartworm prevention? I use Interceptor.
I didn't realize that even using it year round, you have to have a heartworm test done every other year! I need to look for that on line as well.