Gal*Gun: Double Peace, a Japanese on rails shooter that sees you fend off school girls, has a 67.99 microtransaction that gives you the ability to see through the girl's clothes.
As spotted by Eurogamer, the microtransaction adds the Pheromone Z item to the in game store. Once you equip this item you can use it to see through the school girl's clothes, leaving them in just their underwear.
The Steam page for Gal*Gun: Double Peace warns you of adult content before letting you view any of the screenshots or buy the game. It also goes on to describe the game as a; gorgeous anime-styled rail-shooter action. Use your targeting cursor to fend off the advancing girls!” Before giving a brief description of the story mode; Play through the story and see if you can successfully confess your feelings to the girl of your dreams.”
As if the idea of the DLC wasn't bad enough the price gets even more outrageous when you realise the base game only costs 29.99. That's more than double the price of the base game to see anime school girls in their underwear. Together the total cost is a whopping 97.98.
Amazingly the game itself has Very Positive user reviews, the DLC however is at Mixed, and has only been reviewed three times.