I saw something on TV, where a woman recommended a solution of water and vinegar to repel fleas on cats. Has anyone ever heard of that? Does it actually work?

With Frontline being in excess of 40 dollars per three-pack, are there alternative products that are safe and effective without the name and cost?
I should add that we’re treating two cats and a ferret. Last time we bought Frontline, we applied half a dose on the ferret after researching that it was safe. With a full dose for each cat, the pack only lasts a month.

I went to the vet and asked and they said this would be fine. On the back of the box it says "DO NOT USE ON OTHER ANIMALS". I’m thinking about maybe putting just a little not the hole tube.

Is this anything to do with his fleas? Hopefully we got em all now.

I used some over the counter flea treatment on my 1 yr old cat a few weeks ago. It’s the liquid kind that goes between their shoulder blades. I noticed that at the base of each ear now, that there are bright red, bleeding sores. The woman at Petsmart and a vet office said that the over the counter stuff is too strong for cats and can cause "burns" on their ears. Has anyone else heard about this or experienced this before? For those that have heard about it, what should I use to prevent the "burns"?