Awesome that you're doing research before getting a pup!
First set of shots should be DHPP and Corona if I remember correctly. Vet will help you keep on top of future rounds of shots. For continued rounds of shots, cost can vary. I can take a new puppy to get his second jabs at a low cost clinic for $20 or $30, or he can go to a vet that works off of a yearly plan like Banfield and they'll do everything for $25 a month, or I can do a standard vet who will have a little more personal relationship and probably take more thorough care for a fee closer to $80-150 depending on where you go. Which one you do depends on your budget and needs. I do suggest researching and contacting vets now. It helps a lot to find one you like, feel like you can trust, and is easy to talk to with a good reputation.
Heartworm treatment will probably be a pretty steady cost. Flea and tick can vary. You can choose a more or less expensive spot on ($120 supply of frontline to $25 supply of VetMD walmart brand, though I wouldn't recommend either) or you can do more natural treatments as I and some others on this forum have done.
My no chem garlic preventive journey
That thread is a good place to look for more natural flea/tick treatment though what you ultimately go with will depend on what you are comfortable using.
If I'm buying a pup from a breeder, I want papers. I want to see titles and evidence that the parents have been worked and been successful, and I want to see them when I visit the pups. I want to know their registered names so I can research them and decide if they might produce progeny that I am interested in. I would also absolutely require hip, elbow, and eye certifications. I'm not paying the big bucks for an untested dog. Get OFA ratings and stick to dogs that have good ratings and the best chance of producing healthy offspring. When you go to the breeder, the idea is you are paying for the best chance for a dog that is healthy and has a well-balanced temperament.
I wold also consider what bloodline the dog will be. American showline, German showline, a German, DDR, Czech working line? Each one will have tendencies towards different behaviors. Some will be more laid-back, some will be more or less energetic, some will be more driven to want to constantly work. And when I talk about drive, realize that I'm not talking just about a dog that wants to play some fetch. There is a difference between a dog who wants to play some fetch and a dog who has a burning desire to constantly be doing something. If you get a super drivey dog and you aren't ready to work it, it will tear apart everything you love.
As far as other costs, crate, collar(s), leash, bowl, (lots) chew toys, etc. Also consider the costs of training classes. If you are getting a German Shepherd puppy, it needs to have a job. Competitions like agility, obedience, rally, or if you have the commitment schutzhund can be fun and very engaging. If you don't have the inclination to compete, be prepared to at least work your dog's basic obedience and give him a job around the house.
Do some research into dog foods. I would not suggest getting a Pedigree or Purina food. Look into high quality dog foods like Fromm, Acana, or Go!. You can also consider a raw diet. There is more research that must be done for that as well as the commitment to find a wide variety of meats for a balanced diet. Plus the costs associated with these higher quality food options.
And finally remember that a new pup is not just a cost commitment, but also a huge time commitment. Potty training, exercise, stimulation, training, play, all need to be considered. "The Other End of The Leash" by Patricia McConnell is a great book to read if you are looking for reading material.