YOUR TIPS ARE IMPORTANT TO ME BECAUSE I want to buy a Cavalier King Charles Spaniel How expensive are King Charles cavaliers? How Much Does It Cost to Own a Cavalier King Charles Spaniel... The Cavalier King Charles Spaniel is a tiny dog with a hefty price tag. It's easy to understand why this breed is desirable, but many owners aren't prepared for the costs of ownership. A Cavalier King Charles Spaniel can cost anywhere between $1,000 and $4,000 — and that's just for the dog.