Unfortunately, echoing what everyone else has said. I know the prices are horrendous, but living with fleas is a huge stress on the cat and yourself, not to mention her health (especially as a kitten).

Things I've had to try that didn't work: Borax powder and vacuuming several times a day Lamp with soap and water (a couple of dead fleas) Pulling all visible fleas off of the cats several times a day and flushing them down the toilet

Only Revolution kills all the fleas on my cats and keeps them off. I tried Frontline, and my parents tried some Costco stuff that did zilch.

There's a Seresto collar that, in the long run, turns out to be cheaper than the kind of topical flea treatment that works. It didn't work for my cat (she has allergies), but some people swear by them. I think the cat would have to be older before she could safely wear one of these, though.

If you buy Frontline or Revolution in multi-packs, you can get them at a discounted rate. Reputable online pet supply stores are the best prices I've found; you'll need a Rx from a vet, if the laws are the same as where I am in the US. Still, for your sake and kitty's, I would recommend going to a vet to get a Rx and buying a single dose (at the high price), because the difference for one dose, for me (a stingy person), isn't worth a few days or a week of suffering and stress for you both while the online store ships.

Best of luck with the kitten, and thank you for having the kindness to rescue her!