I usually present three options for a blind corner cabinet: a single adjustable shelf, swingout trays (the Hafele LeMans is one option, or just a plain D-shaped wood swingout), or a magic corner unit.
The magic corner and swingouts provide roughly the same area for storage, which is roughly half the storage space of the floor and adjustable shelf in a plain vanilla blind corner cabinet. The three options vary widely in cost. I worked up a spreadsheet for myself to compare the options on the basis of cost, storage area, and utility.
After presenting these options, I also explain (with the spreadsheet) that a 3x3 corner filler and a single cabinet (the same width as the blind corner cabinet's exposed area) offers roughly equal storage area to the swingouts or magic corner in a blind corner cabinet, at greatly reduced cost.
When you break it down to the numbers, most clients choose the corner filler and standard cabinet or bank of drawers. The exceptions are people who just can't cope with the notion that they will give up three square feet of potential cabinet space and delude themselves to believe that they'll actually utilize the blind corner's dead space, costs be damned. Or, alternately, gadgety types that just want a magic corner because it's like a cabinet Transformer. It really is cool.
