A Chewy gift card so she can get exactly what she wants/likes, is lovely. I bet with five cats she goes through a lot of litter!
I have six cats and while I would feel very grateful for anyone buying anything for them, some of my cats have specialty food or litter requirements that would make being gifted treats/food/litter difficult. But in no particular order, as a bona-fide cat lady with a house overrun by cats, here are some things that have made my QOL so much better:
- LeFant Robot Vacuum - it was $99 and the best $100 I ever spent. I run it daily and it completely controls the cat hair and cat litter tracking.
- Litter Robot - this is beyond your budget but, any sort of litterbox robot would probably help a poor soul with five cats!
- Churu Cat Treats - come in a variety of flavors and I’ve never had a cat turn them down.
- Non-textile/cloth cat tree. While the textile is nice it gets SO dingy and dirty so fast. Spring for something with replaceable mats or no textile at all.
- Cat beds - they are surprising expensive!
- Cat shelving kits - only if you know her renting situation and if she is capable of drilling holes into her wall. I have decorated my apartment (I own) with vertical cat shelving and it has been a huge QOL boost for the cats. Our apartment is not small, but it can get crowded with six roaming cats.
A friend got me a cat subscription box a few years ago - it was for 3 months IIRC. It was a fun gift with a lot of cute surprises. I’ll see if I can remember the brand name. I didn’t continue the subscription because I was trying to be good with money, but my cats loved the toys from it.