A few months ago my wife's Macbook stopped recognizing the MagSafe power cord. After some Google searches and a check by a repair shop we concluded it would require a motherboard replacement to correct. Since a replacement motherboard would cost $400+ and I'd already bought an Apple refurb replacement, I sold it "for parts" on eBay.

Based upon the items the buyer is selling on eBay, he will part it out - selling various components separately. Now, I could have done the same thing and maybe made more money. (Or I could have bought the replacement motherboard and maybe been able to net more for a working MacBook - dunno.) Actually, I kinda did as I sold the MacBook with the original RAM and the RAM I put in myself separately.

However, it seems strange to me that there's enough slack in the system for a middleman like my buyer to exist. I doubt the guy is typically selling to individuals repairing their laptops. It's far more likely he's selling to repair shops who use the parts to fix stuff individuals have brought in. I can even imagine people buying multiple dead laptops and cannibalizing one to fix the other. But why wouldn't the repair shops buy my laptop themselves and salvage what they need?

Maybe it's a time and inventory issue. The repair shops don't want to pay for a stock of dead laptops so they have the parts on hand. They'd rather buy one from a middleman when they need something. And the extra costs from buying from the middleman are passed along (with markup) to their client. So from that perspective, my buyer is kind of like a distributor in a traditional retail pipeline.