My wife asked what I spent on tools a couple of times early on. So I started tracking the ROI on my tools.

Every job, contractor price - DIY price = savings. Savings divided evenly across all tools used in the job.

I stopped when my $200 drill hit $30k ROI. I don't remember how long but it was under a year.

As long as the bills are paid and things keep getting built and fixed I have an unlimited tool budget now. It has been 10 years since that experiment and 1 time since then I was asked "why didn't you make work pay for that tool?" "Because I don't want to give it back if I change jobs" was good enough.