If buying a pedigree dog, these do not come cheap! The initial outlay is quite substantial. Then there is the ongoing costs of feeding a good quality diet, vaccinations, insurance for public liability and vets fees (which should be considered a “must have” these days), equipment ie. Lead, collar, grooming kit, bed, crate, toys etc and you must budget for training your dog – classes (and remember, one puppy course is not enough to responsibly train your dog) and maybe one-to-one help if you encounter any specific problems.
If you have decided to go to a Rescue Centre and give an unwanted dog a home then the same applies with the exception of the initial outlay of buying a pedigree puppy. However, most Rescue Centres do charge for you to take a dog so you still need to check out how much this will be.