Drop shipping, where A buys a product from B and B arranges for C, the actual source of the product, to send it directly to A, is a normal business practice for many online retailers. They may keep substantial stock of lots of mainstream items on hand, but their catalogue may also include expensive low-volume items that they don't want to sit and go stale in their warehouse.
A computer dealer may get hundreds of orders a week for hard drives and motherboards and CPUs, for instance, but only sell one video projector a fortnight. If they get eight projectors in stock and have only sold two when a newer, better, cheaper model comes out, they're boned. Better to not offer stuff like that for sale at all.
If the local distributor of that video projector has their act together, though, the retailer can just act like an order processor as far as that product goes, and get the distributor to send the product directly to the customer whenever someone orders one. This can also cause problems, of course, but as long as the retailer obeys the relevant consumer protection laws - just because they never even saw the product they just sold doesn't exonerate them from having to make things right if the thing turns up broken - everybody can, and usually does, end up happy.
So that's drop shipping as it applies to $5000 video projectors. This is drop shipping as it applies to 75 cent books.
And here's drop shipping for people who don't want to keep their eBay account much longer.
EBay is also absolutely jam-packed with people selling sooper sekrit lists of incredible low-priced drop shipping sources. You know - those special companies that sell things really cheaply to Masons, and Jews, and, uh, maybe the homos too - and to you, once you've bought the list! Makes perfect sense!
Some of those outfits are just variants on the multilevel marketing scam where suckers are tricked into paying for little more than the privilege of tricking other people into paying for little more than the privilege of tricking, et cetera.
Others, while they're very good at taking money from fresh-faced new drop shipping entrepreneurs, aren't so good at ever actually sending anything to a customer.
(I bet this post'll attract some really choice Google ads.)