If I was to buy one this is where I would go without a doubt/hands down.
https://www.fowlersmakeryandmischief.com/shop-t-shirts-autographed-pictures-fowler-alone?tag=frame&category=Slingshots
He is a YouTuber and the season finally winner of seasons 3 alone. Super knowledgeable guy, super good guy, and I think probably the best selection of not only slingshots them selves but accessories aswell. If for some reason you can’t click on the link just google Fowlers makery and mischief.