For C&C cages you need 2 things: cubes (wire storage cubes/grids) and coroplast.
Coroplast: local sign shop, Home Depot, Amazon maybe, coroplast shops online, etc. Home Depot is where I got mine. 8ftx4ft piece for about $21. Big enough to make a 3x6 C&C cage (the walls will be about 3-4 inches, hay and poop will fall out easily so I'd recommend getting a second sheet so you can make the walls higher if you're going for a 3x6)
Cubes: Kmart, eBay, Amazon, Bed Bath & Beyond, Target, Walmart, Sears, Ikea,
https://www.storesupply.com/pc-12194-518-14-x-14-white-mini-grid-panel-30101.aspx
Here are the most common bedding options:
-Fleece with towels/u-haul pads/wood pellets. Wood pellets need to be bought over and over again but I heard they last anywhere between 8-10 weeks and are the best at odor control. If you go up to the search bar on this site and you type in "wood pellets" you will see there are a bunch of threads on the topic with great advice and lots of feedback. You can find them at Lowe's, Home Depot, Tractor Supply. U-haul is in 2nd place in terms of odor control. You only need to buy them once. You can use 1 layer underneath the fleece but 2 is preferred.
https://www.uhaul.com/MovingSupplies/Protective-stuff/Furniture-Pad?id=2670 Towels smell very quickly and I wouldn't recommend them. Thicker ones are better but those are more expensive. With towels/u-haul, it has to be changed at least one a week with the fleece.
-Paper bedding/wood shavings. Not great at odor control, IMO. Also, very expensive in the long run.
Here are the guinea pig basics:
-They need to live in pairs or groups. Guinea pigs are social animals and are happier and tamer when they have piggie friends. No matter how much attention you give them, you are not a replacement of a piggie friend. Guinea pigs feel safer in numbers and unless you have tried him/her with several piggies and cannot bond them successfully, you can have it live by itself. Here's everything you need to know on how to bond guinea pigs successfully:
https://guinea-pigs.livejournal.com/3002707.html
Here's more info on why guinea pigs shouldn't be living by themselves:
https://guinea-pigs.livejournal.com/2982433.html
-They need quality hay 24/7. This promotes healthy digestion and is 80% of their diet. It also ensures that their teeth do not overgrow, front and back.
-They need 10-15% of their body weight in veggies everyday (you can figure this out by using a kitchen scale that measures in grams or ounces. This is essential to have. It's not only great for weighing food but it's also need for weekly weighing. Guinea pigs are prey animals so they like to hide their illnesses from us until it's too late and usually the first sign of an illness is weight loss. A kitchen scale can really save your guinea pig's life. You will need to weigh them weekly on the same day every week and record it somewhere so you can look back on their previous weights). They need variety to ensure they are receiving all of the necessary vitamins and minerals. Guinea pigs, like humans, cannot produce their own vitamin c so they need to eat something that's rich in vitamin c everyday so they do not get scurvy. 1/8 of a bell pepper, any color, per pig per day will do the trick.
-Pellets are optional. They are supplements so they are not a must. You can believe what you want, but I and some other people choose not to feed pellets for many different reasons. You can feed them if you like but just make sure they are quality (Oxbow pellets or KMS pellets) and that they only get 1/8 of a cup per day if there are 6 months and older. Pigs under 6 months can receive unlimited pellets.
-Guinea pigs need lots of room. They like to run and popcorn and they live happier and healthier if they are not confined to a ridiculously small, overpriced pet store cage. See the main page of this site for cage size standards.
-Getting any sort of animal means saving up for vet bills. Do not get guinea pigs if you are not 100% you can afford potential vet bills. Every guinea pig will need some sort of medical attention/treatment no matter how well you care for them.
-Adopt, do not buy. Every person that buys an animal from a pet store or breeder is supporting animal cruelty with their dollar. There are thousands of guinea pigs of all colors, ages, and breeds in shelters, rescues, and foster homes. Pet store pigs are usually sick and well cared for. The sows are often pregnant. Shelters and rescues don't let anyone go home with a sick animal, unlike pet stores. They take care of the sick and provide all of the food each animal needs. Most pet stores I've been to confine their guinea pigs to a small glass tank (usually 5+ guinea pigs are in there) with small holes on the side. There is usually only one water bottle, God knows what's in there, there is little to no hay, and a bowl full of junk pellets (the ones with the colored bits, corn, nuts). By adopting, you help many more animals in need. Shelters and rescues use most of their money to buy supplies for their animals. When you buy an animal from a shelter or rescue, you are opening up another spot for a needy animal. When you buy an animal from a pet store, you are letting that pet store stock up on more animals that were bred incorrectly and have been treated and fed poorly. Your options for getting guinea pigs other than from a pet store or breeder are shelters, rescues, friends and family, craigslist, guineapigfinder.com, petfinder.com. Pet stores don't care while shelters and rescues do.
Hopefully, your daughter learns all of this so she knows what to do. Good luck to you!