A string making set up is around $50 with around 10,000 yards of soft poly, I have a five line string rig, just a few 2*4s and some dowels, but you do need a corded drill.
It is called work, if you want to make money it takes time and hard work. It takes me a couple of hours to make a 50 pack. But I do it and love it. Is your rig multiple or single
Doing services involving yoyos for people is not a great way to make money. There’s a lot of people on here that are already experts in the categories you listed and they do it for cheap. You’re better off mowing lawns, weeding gardens, something along those lines until you can get a job. Or ask your parents to start giving an allowance. Say “it will teach you how to manage money for when you have a job”… which is indeed valuable to know.
Keep in mind too, you don’t need new yoyos all the time. I’ve come to realize this and I’m trying to wither my collection to just a few yoyos at a time.
My collection is very small. All my yoyos have been bought cheap from other websites, or have been given free or birthday/Christmas.
I just got my first metal. It was free from a friend. I also have a wooden looping yoyo that was free from him as well.
I’m am fine with just a very small amount of yoyos. But they need to be a few good ones.
Like for example, I don’t want a small collection of say 5, and them be cheap plastics. I’d prefer a small collection of 5 with some Higgins metals and maybe a plastic or two.