Fleas are Back

I hate fleas! We've had some rain then it turned warm so before I knew it, the fleas are back. Thankfully I have some products I use that work great. One is a brand like Capstar which knocks off the fleas within a few minutes and they're all dead. This is great for infestations or even if you just see one. Then you of course have your preventative. The vet wants us to start using Comfortis and I do want to try it but it's expensive for three dogs. Does anyone use it and what do you think?