The magic rules in reselling (at least for me) was that I had to be able to sell something for about 3x what I'd pay for it, and it had to (most of the time) be small. One thing that ended up being exceptional that I never expected was selling "parts" of certain broken items. Some sell better than the product themselves. It's nuts. Also if you're looking at something that is speculatively broken, most others do too. The price will reflect that and you can evaluate the purchase based on the parts market. Try it!