Have you seen Fitch substrate Abi? It's a Uk one that quite a few people use. It's recycled food grade paper - I switched to it from shavings - I wasn't sure at first but am really happy with it - mainly because our Hamster loves it! It's quite soft and I find it dust-free which a lot of substrates aren't. Carefresh isn't actually paper, it's cellulose - the Fitch is just paper substrate. I still use torn up white toilet paper for nesting material and our hammy uses that to build his nest but he likes to take some of the Fitch substrate in for his nest as well and has built a huge nest lol!
I get the 10kg bag which lasts me about 6 months (doing Erin's cage cleaning method). Just think it's something that could be shared with your Sister maybe. You buy it online either direct from the manufacturer, or from Amazon (where it costs a pound or two more). I think if you live nearby the manufacturer you can just pick it up and get it even cheaper.
Fitch Recycling - 10kg Single Bale Fitch Paper Bedding For Smaller Critters - Fitch Pet Bedding