For must have items
Cage:
-A cage that is the appropriate size for a number of guinea pigs you are getting
-Fleece/paper/wood shaving bedding (whatever works best for you)
-Water bottle/bowl (water bottles are less messy)
-Ceramic dish/bowl for veggies, fruits, and pellets
-Hay Rack (could be store-bought or DIY, but make sure it's big enough to accommodate your piggies, or else you'll find yourself filling up their hay racks A LOT)
-Hideys (make sure you have at least 1 per pig)
Food:
-Hay (80% of diet)
-Veggies (15% of diet)
-Guinea pig pellets (5% of diet, must be appropriate for their age*)
For BEST items
-Pellets: The brand Oxbow is AWESOME. They have young and adult guinea pig pellets.
-Hay: You can also buy this from Oxbow, but it's cheaper to buy it in bulk from Small Pet Select, KMS Hayloft, or a local farm
-Dishes/Bowls: Buying them from pet shops are a bit expensive. You can instead buy small ceramic dishes made for cats/dogs at Dollarama or dishes/bowls made for humans from stores like Ones or Winners.
-Hay Rack: Pet store hay racks are tiny! Try bending a C&C grid or buy some sort of wire rack from Dollarama.
-Cage: C&C cage. There's lots of info on them in this forum.
*Guinea pigs that are under 6 months should be eating alfalfa hay based pellets, while guinea pigs above the age of 6 months should be eating timothy hay based pellets.