I am a house sitter, and I charge £35 per day plus travel, and I stop in the house 24/7 apart from going to the shops etc. Iam fully insured,police checked and have referances. Your best bet would be is to ring Animal Aunts or Animal Angels and get a price. They both have websites. I would say 99% of my clients have horses, cats, chickens etc, so a bit more to do.
I look after dogs as a "side line" to my "looking after horses" activities. I have very many regular customers and I charge £10 per day per dog or £15 if the customer has two dogs. I regret the latter tariff since it's bloody hard work and the dogs I'm looking after at the moment are keeping me on the ball 24 hours a day (two of the dogs howl when left alone)!). I think I charge a bargain rate, hence my "popularity"!