I would be interested in some for my PS M-10 45ACP if the price was right.
That being said, the market for such a magazine is extremely small and likely not worth the ass pain of securing and defending a patent. Furthermore, a patent would drive the cost up and subsequently make your market even smaller. If this new magazine is truly new and not just a modification of existing grease gun magazines, then I would recommend licensing your idea to an existing magazine manufacturer (e.g., Shockwave). For reference, read the dozens of pages in the Z-mag development thread to get an idea of what it really takes to manufacture a quality magazine.