Cheap way to treat cat fleas?

[DMRick]

We use Advvantage on our fosters, and within hours of my putting it on, the fleas are on the floor waiting to be swept up. I just use the plain, because once I worm them separately, and take care of the ears with ivermectin, there is no reason to give them anything but the flea med. Our foster cats stay inside (and people promise that when they adopt, but of course once they are out of my hands...) and it's a lot less expensive than if they go outside. We (our no kill shelter) buy our Advantage in bulk, so we measure it ourselves. I think it works great. I keep the fosters in a bathroom with no carpeting with the entrance floor flea sprayed for 48 hours, to prevent my house from getting invested. So far so good. Some of our babies are bitten so bad and have so many fleas we have to dip them first..and the water runs red. It's really sad how bad some outdoor cats get.