It's so tempting to keep them all! But no, I can't keep her! I have two possibilities for homes for her. If neither home decides to take her (it happens), she'll be up for sale.
All my animals (8 chinchillas, 2 guinea pigs, three cats, and a dog) live in a studio apartment with me, with only cutrains separating the rooms (kitchen/living room/bathroom). So yes, I do keep them all together. Marley is the most curious about the animals, but Willie and Rueben have grown up around them, and just ignore them now. Marley almost never stalks my chinchillas (sometimes though!), but I used to have an ugly sickly hairless rat that she wanted to eat so bad (she couldn't care less about healthy rats). I think she knew he was weaker than the others. My dog adores my chinchillas and will "get" (chase, hold down, slober on) the kitties if they get too interested. That dog adores them a bit too much though, she let them out of their cages at night to play with them. She never ever hurts them, and they're not scared of her, but she does slober on them and they don't like that! I have to figure out some new latches for these cages.
Ask questions and learn as much about them as you can, then decide. They are not for everyone! They're spunky and curious, but will probably never come to you when you call them, and hardly ever get cuddly-sweet. They chew up everything, and have no regard for where they poop. It can be hard to find a vet who knows anything about chinchillas. Care is relatively easy - if you're used to rodents. I grew up with rats, hamsters, etc. Clean cage, fresh (high quality!) chin food and hay, clean water daily, frequent dust baths, lots of play time (in a chin proofed room - They chew!). Temperature needs to be kept below 75 degrees (they can die from heat stroke).
They do make very fun pets for the right people.
I deffinately suggest buying from a reputable breeder or rescue (there are chins in rescue because people don't realize you can't just stick them in a cage, never give them dust baths or exercise, and feed them rabbit food!).
Go to chins and quills, they will help you learn what you want to know!
Cost varies greatly between $75 and $500, depending on quality and color.