Every area has bargains. If you love photography, start with lesser-known artists' work, and be very selective in what you choose. Keep your eye on your goal and be disciplined about how much you spend. Know that you can always trade up. If it's rare, or might become rare, it's more likely to hold its value.
Rarity is the hallmark of a strong art or collectible investment.
Strive to find the rarest examples, or the rarest complete collections, that you can. The main reason why Chia Pets aren't a good investment is because they are not rare. They are a mass produced, machine-made item, with no variations, special characteristics or charm. There are exceptions to this rule, such as Beanie Babies, or Star Wars toys. But the market for such items can truly be a house of cards, collapsing without notice.