I do like to live large. I tend to overstock items. Between luxury balls, timer balls, ultra balls, net, dusk balls etc I may easily carry 70 pokeballs of various types with me. You can also never have too many max repels. I also buy vitamins to help me ev train. And of course I like to have a nice long menu of every refreshment imaginable so I can serve moomoo milk, vending machine drinks, all of the pokecenter goods-- whatever the situation calls for. No less than double digit quantity for each item, my babies must have anything they could possibly dream of at their disposal.
This does cost money. So I bought the luck incense from the reformed plasma grunt in driftveil city to double my earnings. Do that and hang out with the Riches in Undella Town where you can battle them for high stakes and sell them priceless relics you found diving into the ruins. Cheren, rematches with the elite four, Cynthia etc also of course pay well.