I am not a handyman, but when i purchased my rental it needed work so i went about completing my tool kit with a purchase as you go mindset. There are plenty of hardware stores around town so i decided not to buy anything until it was needed. By the end of the project here is what i ended up with:
2 pairs of work gloves (one heavy duty pair with short fingers for the dirty work, one normal rubber grip pair)
Hats for working in the sun.
Respirator.
Caulking gun (The cheap one, wish i had @Jim K.'s advise back then).
Impact driver.
Drill.
1 Hammer (there are instances where i wish i had smaller / bigger hammer, but come on.... one does the trick).
Measuring tape.
Crow bar.
A few putty knives.
Lots of gardening tools (2 rakes - hard and soft, hoe, loppers, 2 shovels etc)
A good level tool.
Lots of razors (man, razors have many more applications than just shaving my dumb face haha)
Here is the way i looked at it:
I am not in a business of working on other people's properties, so i wont need everything under the sun (or home depot's roof). So if i purchase things i THINK i will need - i am running a chance of wasting money on something that's going to end up sitting in my garage without any use.
On the other hand, since i already have a project on my hands that requires certain tools - i know that i will put these tools to use at least once. At the very least, buying these has made my life easier for the time being. Also, since the scope of work was very general, i figured there is a high probability that i will require similar things in the future, so i did not feel bad for spending money on these items.
EDIT:
I think i should also mention that a few years ago my car got stolen and recovered. The crackhead who stole it went on a ****in spree and had a **** ton of stolen items in the back that included a circular power saw hahahaha! I have never used it and quite frankly - don't know how. But seeing that i'm not a complete idiot, i'm sure i can figure it out if i end up needing it in the future lmao!