"I figure if I buy the tool for a specific job, I still own the tool after the job is done."
We think alike.
I've typically done the same thing my entire life. It's a good way to acquire things you'll need or use over the years. These tool acquisitions just get written into the job if you are doing it yourself. Savings is the overhead and profit of a contractor doing the job "on the books".
Any hired out work will cost more and rightfully so as no business survives without decent profits.
It is nice to do some of ones work in house, the incentive being the previous. When time is short, it needs to get done, no choice to hire out, just you don't gain any tools or the like either.
Friend is in my shop with his nice 62 impala ss. He was going to send it to a shop to remove the existing motor, replace with a professionally rebuilt one, to his specs. Instead he's got an new engine hoist, few other sundries he did not have and doing the work himself gets things done exactly how he wants it.
I bought a used craftsman compound miter saw, seen some use but is completely accurate still, plenty good for all kinds of work still to be done.