As such when you buy kitchen cabinets online they will normally come flat packed meaning that you get all of the raw materials you need such as the wood and the screws and pegs, but that all of them will be flat in a box as opposed to ready-assembled as cabinets. These are ready to assemble cabinets and they save you money not only in the postage but also in that you haven't paid for the liberty of having it ready assembled. Thus ready to assemble cabinets often are also some of the most affordable kitchen cabinets.
Of course this does then mean you have to build the ready to assemble cabinets yourself but this is far from a hardship. When you build your own cabinets this is normally a fairly simple task that shouldn't take you more than half an hour. If you have several ready to assemble cabinets to construct then this will normally be quicker each time you complete one as you get to grips with how to build them and what to do with the parts.