Every pet owner should establish a relationship with a veterinarian. This is important for many reasons. First and foremost, your veterinarian will make sure that your pet is up-to-date on necessary vaccinations and free from disease. Just as you would vaccinate a child against polio, you need to vaccinate your pet against disease. Puppies and kittens need a series of shots so that they can build immunity as they grow, they need to be wormed, receive flea preventative, rabies vaccine, and get checked for diseases such as heartworm, feline leukemia, etc. Trust me. It is worth the expense.
Yes, it may seem expensive to you, but as anyone who has attended college will tell you, schooling is expensive. And many veterinarians who have been in practice several years may still be paying off their college loans. Then you have to pay for the rent, utilities, supplies, the receptionist and vet tech, insurance, health care, and make enough for their own paycheck.
Another reason you need to see a veterinarian is that you need that relationship in case something happens to your pet. It could break a leg, swallow a poison, get attacked by another animal, the list can be quite long. If you are not a client with an established veterinarian, it is unlikely that they will see you in case of an emergency unless you can pay ahead of time. And if you cannot afford routine veterinary care, you should wait to have a pet until you can afford to care for it.