Here is an interesting puzzle.
Edhellen Armoury sells weapons for LARPs such as Belegarth and Dagorhir. They charge about $25-40 per weapon depending on size. They sell weapons primarily through the web site, but since they are based near here in Illinois, they also sell weapons through one of the local gaming stores, Dragon's Table. Most of the weapons they sell on the site are only legal to slash with, not stab with, because they do not have the required "stabbing tips." It is possible to get a stabbing tip added to the weapon for $10 extra.
A stabbing tip is simply an extra piece of foam that goes on the tip that makes the tip softer. The marginal cost of adding it is certainly far less than $10. (This is not the puzzle - lots of products have "extras" that you can get that cost far more than the cost of adding it, as a way of segmenting the market and making more money. For example the 16 GB iPhone costs $100 more than the 8 GB iPhone, even though the cost of 8 additional GB of hard drive capacity is far less than $100.)
The puzzle is the following:
The existence of the option to buy stabbing tips for extra is not listed anywhere on the site, and none of the weapons that are sold at the Dragon's Table have them. In order to find out that they exist, you have to call them, and then they tell you to buy the items as normal and put a "Special Payment" in for the stabbing tip. The question is: why do they make it so hard to find this information? There are other instances of companies making information about particular products hard to find, one notable example being the Starbucks "Short" latte, as a form of price discrimination. But unlike those other examples, Edhellen makes more money off the swords with stabbing tips, not less, so why would they want to hide it? The only thing I can think of is that the demand isn't high enough for it to be worth putting on the web site, but that's surprising, because I've seen lots of weapons at Belegarth with stabbing tips. (In any case, even if people didn't want the more expensive stabbing tip weapons it might still be worth putting them on the site, because of the "decoy effect" - seeing a more expensive option makes the other option look cheaper and more attractive by comparison.)