Is there software, that you've paid money for, that is so good that you would have paid even more for it?

Yes, the turbo family of programming compilers.

They have active debugging, (you can step through the code one line at a time to find errors)

Tag & Rename has been an extraordinary bargain for me. A one-time payment of $25.00 and I have gotten every new version for the past 8 or 9 years. It never disappoints and since I collect tons and tons of music, I use it constantly.

Guitar Pro. I don’t use it as much as most people (I learn directly off of sheet music or “hard” tabs), but it is helpful in arranging music. 50 bucks, one time.

generally i feel like asking for my money back. however, i have found free software that i would gladly pay for.

open office for example, awesome office suit and its totally free and has loads of plug ins.

Turbotax

Battlefield 2 – Cost me £20 four years ago, and I still play it.

Spotify Premium. I pay monthly for listening to music without ads.

Games that kept me interested playing for years.
Tigers on the Prowl
Panthers in the Shadows
Myth: The Fallen Lords
Myth II: Soulblighter
The Dominions series by Illwinter
Ancient Domains of Mystery (only costs a postcard)
...