"...to save money"
IMHO, the OP has already stated their reasoning by the title of the post.
I'm not going to offer my opinion on h/her reasons, but just to reflect upon our personal situation, as being part of a Sheltie rescue group for many years.
We first got involved upon the passing of our second Sheltie, who at the age of 11 developed kidney disease (as many canines do).
At the end, I was giving him IV's (yes, me - not the vet; however I did get instructions on how to place the needle in his "scruff" and hang the bag) for the last 4-6 weeks of his life. He was part of our family for so many years, could I do less?
After his passing, we got a "store bought" Sheltie (the first two were from breeders, but no longer in the business), who was a real challenge. "Our little girl" was a spunky pup, who grew into a spunky adult. We looked for a solution, and for the first time considered a second dog (hoping the other dog would become her "buddy").
However, after having more than a few pups (which are great) and getting older, we started looking for an adult Sheltie who would become her "partner in crime".
It came to pass that we found a Sheltie rescue group and we started to look at their available dogs (on-line). This one guy, a bit older (at 10 years) was constantly being "passed over" due to his age and the fact that he had KD (kidney disease). While he did have some folks show interest, they shied away not due to his age, but rather his KD situation.
After a lot of thought and soul-searching, I (e.g. we) decided to adopt him to try to let him live his remaining life as best we could. I made the commitment that I would not try to extend his life through "extraordinary measures" (as we had done with our previous dog, who I administered IV's), but to make the best of it. My hope is that he would remain alive to see "4 seasons".
As it turned out, he became a "best bud" to our little girl and I was able to uncover some attributes that were unknown to the foster parents. He loved to catch Frisbee, and able to go though the jumps (I have a set of gates for practice). The foster folks were unaware of what he could actually do, and he certainly showed a "lust for life" as he went through his exercises.
My hope for him was met. He came to his end after 10 months (which covered four seasons), and while I had regrets on putting him down, I knew that it was the best for him.
After his passing, we still wanted to get another Sheltie (via rescue) and put our name back on the list.
About two months later, I was called at work from the rescue group with an emergency situation. They were called out on a case in which a Sheltie who had a health problem needed to be rescued ASAP. While they understood that our previous rescue was related to our prior experience with KD, this case was different. The Sheltie had been thrown off an apartment balcony as a pup, and his right rear leg/thigh was shattered. He had received surgery (pins inserted), but he walked with difficulty, and at the time was 9 years of age.
He was currently in a home that had two toddlers that would (for fun) pull on his "bad leg" to make him "growl/snap" (they thought it was fun).
The rescue group was just trying to get a foster family (DW/me) to take him for a short time to get him out of his current situation.
I agreed (DW didn't know of his "disability" at the time, and didn't appreciate my decision when I told her).
Actually, he turned out to be the perfect "partner" for our little girl. He/she loved to play "pull rope" and would chase each other around. With his leg, he was not fast, but our girl let him "catch her" as they ran together.
As it turned out, he had a normal lifespan of fourteen years (normal is 10-15 for a Sheltie) and at the end suffered from aches/pains related to his age, and his long suffering leg/thigh. Yeah, I had tears for all my dogs over the years when they passed, but I had more so for Jessie.
As a follow-up, we adopted our next rescue. Since I had taken two "problem dogs" from the group in the past, I went to the top of the list to see if they could match us with a younger (and healthier) Sheltie.
About six months later, we adopted our current rescue (and our "old girl" is still kicking). We adopted him at three years of age, when his former owner (a widow) had to go into care due to her Alzheimer’s.
He's now age six and our old girl (who started this whole rescue thing) turns 10 in February.
We've had six Shelties during our 40+ years of marriage and even though things were (financially) tough - especially during the early years, we would never put down a part of our "family", due to financial necessity. There are other ways (via rescue) and other families/individuals who are willing to take dogs (or any animal) who needs end of life care. I can't believe I/we are the only ones.
Just my opinion on the question at hand...