Oh gosh, now I want a Greyhound!
We have two dogs. One is a mutt who showed up in my front yard one day with a broken leg. As a best guess, she's lab and Staffordshire Terrier, about 80#. Other dog is from the shelter and best guess is Border Collie and curly coated retriever. The first one cost me the most her first few months, dealing with the broken leg, spaying, etc. I've had her for over 10 years now and she's been very low maintenance. I do keep her on a joint supplement to help with the residual effects of the broken leg, which was actually her pastern joint, and the arthritis in that shoulder, presumably from the same accident. The second dog is about 50#, which I think is a perfect size for a dog. His adoption fee was $70 including neutering and first shots. They both eat about 2 cups of food per day. They get the CostCo brand, which is actually a pretty good food, compared to the more expensive kibbles you can buy. They seem to go through a bag every 5 weeks or so, for $29 per bag. They also get CostCo dog biscuits, which are like $10 every couple months, and I might buy them a couple toys each year. Places like Big Lots and TJMaxx usually have good dog toys for much cheaper than PetSmart.
I haven't treated them for fleas in years, and have not seen a single sign of fleas, though they are free to go outside whenever they want. This has held true through living in 3 different houses in two different states; don't know if I'm just lucky or??? The one dog is white, so I'd notice if there was any flea crap in her coat. The BC mix I clip myself during the summer, and I bathe them both myself, so grooming costs are nil (already had the clippers for my horses, but an excellent set that will last the dog's life and then some is about $120).
Also, with my vet's blessing, they only get shots every three years. If I have to board them, then they do need Bordatella each year. Boarding is $12/dog/night, so it does make going out of town a little pricier. Licenses are $19/dog/year.
Things like treating for cancer and so on are a personal choice. A couple years ago, we had renters split town and abandon three dogs in their back yard. One lived with us for a few weeks, then a local boarding kennel offered to foster her. She got sick, it turned out she had a huge tumor. She was an older dog and at that point, I would have had her PTS, but they spent like $2800 on surgery for her, then she died the next day. To me, that was above and beyond anything they needed to do, and probably more than I would do for my own dog in that situation, but it's worth considering how you would deal with those end of life decisions when they collide with big vet bills.