Alternators are very basic devices that are well understood and made of simple materials; copper, aluminum, a bearing or two, a voltage regulator that was essentially perfected in the 1970's (or not; some electrical systems use external regulators). A rebuild generally involves replacing all wear parts whether they need it or not. Hard to go wrong with any brand, really. Alternator rebuilders once dotted every city with more than two taxicabs. There is no real value in the brand; anyone can do this.
I usually buy the kit and rebuild them myself. Much cheaper, but the point is even the parts aren't expensive, so it's there's not even much incentive to cheap out there. They don't even pay much for the Core. You're paying for labour, shipping for a relatively heavy device (that [censored] copper again) (twice), and profit times three entities (rebuilder, wholesaler, retailer). Fifty bucks on a $300 retail item is in the realm of a rounding error.
