I did it! Granted, I have easy hair (long and slightly wavy, though never with waves in places where any sane person would want them), but still... this is HUGE for my budget! I was spending $72 (including tip) per hair trim every 6 weeks, plus the gas for the 20-minutes-each-way drive, plus the time to accomplish the drive and the trim. And every other visit, I'd get highlights, putting the total at damn near $300. But no more!
Yesterday my $12 hair scissors arrived from Amazon. I watched a bunch of YouTube videos, and after a shower today, I did it. 1.5" gone, for 5 minutes of my time, and it still looks good enough to go to the grocery store today without a hat or a pony tail. Thank you all for the motivation. My hair was 10% of my monthly spending, on average, and that's now 10% that can go toward FIRE. (I know, I know, please give me a retroactive facepunch. I desperately needed it.)