Cheap cat scratching posts that actually work

First — I'm sorry about the job situation, that's genuinely stressful, and keeping your cat sorted without spending much is absolutely doable. The reason most cats ignore scratching posts comes down to three things: too short for a proper stretch, too wobbly to trust, and the wrong material. A solid sisal post that's at least 60cm tall will fix the problem for most cats. Before I point you at the cheapest option that actually holds up — how big is your rescue, does she scratch vertically or horizontally, and what's she currently going for at home?

Perfect, that tells me a lot. Vertical scratcher going for the sofa arm means she wants height and something firm to drag her claws down. The carpet habit is secondary — once she has a good vertical post she usually drops that. What's the sofa covered in, fabric or leather?

That's enough to get this right. She's going for rough fabric because it mimics sisal — which means she'll take to a sisal post quickly, you're not fighting her instincts here. My recommendation is the Petmaker Sisal Scratching Post, roughly 60cm tall, solid base, wrapped in natural sisal rope. It comes in under £15 on Amazon UK most of the time and it's heavy enough at the base that it won't tip when she leans into it. That stability matters — a wobbly post gets abandoned fast. It's not fancy but it genuinely does the job, and for a 4kg cat it's exactly the right size for a full stretch.

Put it right next to the sofa corner she's already using — don't hide it in a corner of the room. Cats scratch where they scratch, so make the post the easier option in that exact spot. Rub a tiny bit of catnip into the sisal if you have any, but honestly just placement does most of the work. Once she's using it consistently after a week or two, you can inch it a few centimetres away from the sofa if you want. Don't move it across the room too soon or she'll go back to the couch.

It's worth watching but I wouldn't spend more money on a horizontal scratcher right now. Often the carpet habit fades once she has a good vertical outlet. If it persists after a few weeks, a flat piece of sisal matting — sometimes sold as door mat offcuts — costs almost nothing and works fine laid flat on the floor. But start with the post and see how you get on. One thing at a time, and your budget is better spent getting the vertical sorted first since that's her main preference.