As Steve himself admits, you can also get tartan kilts with slash pockets from

http://www.sportkilt.com

He considers their pockets to have plagiarised his, and there is a thread about that somewhere, but absent a patent, there is nothing he can do (I'm a patent agent, so I know whereof I speak). Plagiarism is not really relevant to structural features, only patent infringement. Getting a patent is an expensive process that depends on proving that you thought of it first, and if your competition is already on the market then you are already too late.

Of course, the SportKilt is a lightweight poly-something kilt suitable for hot weather and competing in highland games, but doesn't quite pass for a traditional kilt. For full disclosure, I own one myself and mine does have the slash pockets. It cost less than half the price of a comparable Freedom Kilt, but obviously contains much less (and cheaper) fabric and takes less labour to make.