A couple of the folks mentioned survival-friendly gear, and I couldn't agree more. Marketing for the podcast and the forum are excellent ideas of course, but I personally have a shopping list of gear I'm slowly acquiring. A lot of this can be branded or even modified and sold by the Gear Shop. I would imagine that it's much more challenging to get some of these items made, but if I could get them through the TSP Gear Shop, I'd certainly prefer it!
Leather sheaths come to mind -- there's a group out there that makes high-end aftermarket sheaths for popular knives, adding better attachment and retention options than the factory sheaths, and adding firesteels. If so inclined, you could do something like that, making them to order. If not, I imagine you could source some simple, quality sheaths and stamp or brand them with the appropriate graphics. I purchased a hand-customized knife from a fellow on YouTube who purchases custom-made blades from the Svord company and then adds his own very simple scales and plastic sheaths. I think he buys the blade blanks in sets of 20 or so. I love knowing that it was the labor of love of someone I respect, and it's one of my favorite knives. The manufacturing challenges are (relatively) minor, and stock on hand is kept low.
What about selling non-branded outdoor gear? Another guy I found through YouTube, who was later interviewed on TSP, runs a very interesting online shop, selling gear he would or does use himself, in addition to his own designs. Would it be possible to sell the gear used and trusted by some of the fantastically experienced folks on the forum? This would presumably involve buying in bulk and keeping some stock on hand (and the associated financial investment), but I know I would be fine with a "group buy" type of system, getting enough buyers together for an order of something in particular, but doing it through the Gear Shop so that people I know and respect are earning the profit on it.
-Justin