Very few jewelers are familiar with pearls in any real way, and many of them cannot even tell you how different pearls are cultured. Additionally, I've never seen a brick and mortar jeweler who didn't overcharge for pearls, often of substandard quality.
I would check Pearl Paradise online. They have some of the best quality pearls at some of the best prices. Freshwater pearls will be the best price, though even at gem quality, their luster will not be as metallic as akoyas. Akoya pearls are saltwater pearls, and usually have a very metallic shine - to my eye they are unmistakable. South Sea pearls are generally larger (bead nucleated like akoyas, whereas freshwater are nacre all the way through) and have a satin-like sheen. They are often white but also come in shades of gold. Tahitian pearls are also larger and come in varying shades of grey/silver, peacock, brownish, and almost black.
If I were to invest in pearl studs, I'd go with the highest quality akoyas I could afford. And make sure you know what size you want, as it isn't as easy as one might think to estimate a mm size. I find that they look far larger on my ears than they sound, so I generally go smaller, but many other people prefer larger sizes.
