1st point of my CB'ing....
I have a very, very old Craftsman shopvac. It has to be at least 80's vintage. It's red if that means anything.
The original filters long gone, and the unit is so old, nothing on the market fits. So I took 2 of those yellow, microfiber clothes for cleaning (the 10 pack from Costco just keeps giving) wrapped them around the filter stump cage and cranked 6 zip ties to lock em' down. I used 2 so I'd have layers, for better filtration
Now I can use this antique to remove junk off the floor, and even wet stuff at that. Sure the clothes will get wet, but so what? I just pop the top off, flip it up side in the sun for half n hour n they're dry again.
So to sum up the investment...The bag of costco clothes was 4 or 5 bucks about 5 years ago. The zip ties I liberate from work, and they only cost the shop about 4-10 cents a piece depending on width n length...so zero. When I get them wet, the power of our solar systems star does the work to dry them for free.
2nd exercise in CB'ing...
I collect the all the spent drill bits my mechanics toss on the floor. These guys are entitled AF.

"Why would I spend a min to sharpen one, when I can pull a fresh one from the Wurth cabinet?"

I take them home, and sharpen them myself. I believe they're made for Wurth by Norseman.
They look identical. The cut the same. And they're free to me.
3rd times a charm...
I will rebuild almost anything I can get a kit for. The front calipers for my Gen 1 Tundra, are priced from 115$ to 245$ depending on reman supplier. And that's my wholesale discount. Suggested List is as high as $488...
The seal kits are under 50 bucks for the both sides, again, @ wholesale. I can have them off, cleaned, apart, and back together in a couple of hours...If I don't bother to paint them.
last but not least...
My free to me Yamaha 2wd ATV...I got it out of a fella's backyard, with 3 flat tires, a spare frame n front plastic, and 3 extra parts engines. It had sat, up to the belly pan in mud for almost a decade.
I took one engine apart to see how it went together, then took the one in the bike apart with the knowledge I'd gained from the parts unit. I used the parts unit as a donor, to repair the bike. The timing chain was stretched really bad.
I also reconditioned the rear axle shaft with some Devcon Titanium putty (again, donated by work) turned it down on my old 9x20 and put new bearings n seals in. I have had to make a few online purchases to get it up to snuff to ride though...but even still, I'm into this machine for less than 500 bucks. PLUS, I've learned a bunch about ATV's that I didn't know. And that is priceless in itself. Knowledge is power.