Cheapest price for frontline plus

I've been searching for months to find the cheapest price for frontline plus. I think that Amazon is my best bet. My Vet seems to be the highest. I guess they need to make some money off it to stay in business. I have a Golden Retriever and a small Chihuahua. We live in the woods with a large field near-by. We get a lot of ticks! I make sure to frontline both dogs monthly. It only takes a few minutes each month and it's a must. Bottom line, I would recommend Amazon for the cheapest price for frontline plus.