The biggest mistake you can make is buying no-name or low brand recognition cables. You'll find it very difficult to resell them.
Best to buy used or ex-demo and trade them up every few years. They don't lose much money after the first purchase. Nothing to wear out either.
Try to buy cables suitable for your gear which don't come on the used market often.
These are the winners.
I'm very lucky because my dealer let's me bring home cables to try out.
My investment in cables is way more than 100% of the cost of my system but if you want a highly revealing system that's what's needed.