I love our guinea pigs they are a bind and the dd's soon got bored of them. Which means its me that feeds them and changes water, cleans them out and plays with them.
We got them at the wrong time of the year and they currently live in our hallway as they couldn't go outside. We will be buying a hutch in the next month or o and putting them outside in the day and building up to them staying outside except when its freezing.
We have a large run for them and we tent peg it down as we have two dogs, funnily enough the one we thought wouldn't be interested is the one that this to get at them if he's about, the Labrador, the terrier just stares at them.
I'd say on a weekly basis they cost more to feed than the dogs, the dogs have one bag of food between the two of them (due to allergies only dog food lab can eat is sainsburys or aldis own), but the guinea pigs food is £8 for a sack which doesn't last as long as you'd think, and plenty of fruit and veg each day, plus fresh hay daily and then sawdust twice a week to be cleaned out.
we just have the pets at home large in door hutch as we have the dogs we can't have anything that they might escape from, as I can't imagine the look on the dd's face if the dogs did get hold of them.
We have been recommended by so many people to get guinea pigs for younger dc rather than rabbits, even by rabbit owners. ours were 6 month old boars from the rescue part at pets at home, rather imaginatively called bubbles and squeak.