I can’t guarantee everything on my list here will be BIFL, but I’ll go through the last couple years of my Amazon orders and pick out purchases that were definitely game-changers for $25 or less.

Scrubbing Bubbles Fresh Gel - it’s a little stamp that leaves a dollop of gel in your toilet bowl and it keeps the toilet clean for weeks. I tested it once and I think one stamp kept the toilet bowl looking clean for about 2 months.

A staple-less stapler. It won’t go through more than 4 sheets at a time (at least mine won’t) but I find that I rarely have more than 2 sheets of paper that need to be attached to each other https://www.amazon.com/dp/B00KYP2OYQ/ref=cm_sw_r_cp_api_glt_i_CMPKKVFRQMENSPMYS1FH?_encoding=UTF8&psc=1

(edited cuz apparently I don’t know how to embed links on mobile)

Sleep mask

6ft long charging cable. I’ve been pretty happy with the Amazon Basics one, which has lasted me for 2 years now.

TubShroom

Yea, there was such a thing as a paper welder then. I think the two best ones today are the ones that make a hole and fold, or those that crimp like this one.