I've had good experience hiring designers. Designers seem very much underpaid for the amount of expertise they have, so you'll often get some good deals if you look hard enough. I've had an argument with one designer that I wanted to pay her X amount hourly, and she wanted that much daily.

Still, it's something like $80 for something that takes me a week to do and tweak, and some experienced dude can get it done in 1-2 hours.

But for photography, I often do it myself. Photographers here are often overpriced, as in you could end up paying hundreds of dollars for similar quality as you'd get for half an hour and a good phone camera. The people who are passionate about it often do it part time, and the people who do it for a living often focus on improving negotiation skills. YMMV.

If you're doing something with game art, there are places like https://itch.io/game-assets

Envato has some good quality stuff too: https://elements.envato.com/