I have three cavaliers.
If you just have one pet,and she gets plenty of time and attention,then one is enough for many people.
The more dogs you add to your home,the less attention you can give each one individually.
Three lots of pet insurance is expensive,feeding three is expensive,as is grooming products and the effort involved in maintaining them in good coat.
The workload involved in multiple dogs is a heavy one,washing dog blankets,beds,crates etc..not to mention their exercise needs.
Above all else,when taking on multiple cavaliers,you need to be aware of health issues within the breed.
I have one four year old with Syringomyelia(SM),a common inherited neurological condition,where cavaliers develop fluid filled cavities on their spinal cord and can cost up to 1,000 per year in medication costs for the uninsured.
The decision to add more cavaliers to a household is not one that should be taken lightly and only choose a cavalier from parents who are fully health tested, which means at a minimum, both parents mri scanned,cardiologist heart tested and eye tested.
If you can't find such a puppy,then maybe consider taking a rescue cavalier who has been spayed/neutered.There are cavaliers of all ages in dire need of a loving home as rescues are being inundated with surrenders due to the economic downturn.
They're a wonderful little breed and adapt to family life very quickly.