I'll second Amazon, I've gotten a number of the earrings that I regularly wear there. Etsy is also a solid choice if you're looking for something a little more niche. I have six in each ear, and they're mostly a mix of Amazon and Etsy with a few from my mother sprinkled in. Simple studs and simple hoops work well with just about anything, they go well enough dressed up at work or in a tank top while working out. Make sure to get Titanium or surgical steel, not something poop that he might have a reaction to.