Another golden retriever owner. She is our first golden and she is a wonderful dog. They do have a long puppyhood but are pretty easy to train. We got ours from the Humane Society when she was a puppy.
Since this is your first dog ever, you might want to consider rescuing a dog past the puppy stage. They require a ton of attention and training.
For costs--according to my vet, goldens are prone to allergies and often have trouble with their ears. Sunny had to have steroids last fall when her allergies got particularly bad which can add to your vet bills.
I would suggest calling a local vet and asking for their prices for things like yearly shots, well dog visits, nail trimming, heartworm pills, etc. That will give you an idea what the cost will be per year for a healthy dog. Of course, illness will add to that cost.
For food--I buy a huge bag of lamb & rice dog food about every 6 weeks. Oh, yeah, dogs with allergies often need special food.

It costs around $45. Then you add in the toys, bones, etc. I've found it better not to keep track of that cost.

You'll also need to get the dog groomed or learn how to take care of the matted hair yourself. A crate is a great investment if you do get a puppy--it really helps with the potty training.
I really do recommend a golden for a first time dog owner. They are friendly, anxious to please their owners, good with kids, and smart. (But not TOO smart--at least in our case.) I've had many different breeds over the years and there is now a special place in my heart for goldens.