Idea: Coupon Bot

As many of you are surely aware, Dota 2 Dispenser is an automated Steam account collects spare copies of Dota 2 from donors and gives them to anyone who requests them. Inspired by that bot, as well as by the huge flux in unwanted coupons that has arisen from the new trading card system, I am thinking about making my own bot for distributing coupons.

Here's how it would work: Gabe has an unwanted coupon in his inventory. Gabe adds the bot account as a friend, starts a trade, and gives the bot all of his spare coupon(s). This works the same as the Dota 2 bot. However, unlike the Dota 2 bot, there are two additional problems that need to be dealt with: a) the bot is giving away more than one type of item, so there needs to be a way for the user to specify what game they want and b) the bot will need some mechanism to prevent jerks from just taking all of the coupons (since it can't simply check if the user already owns Dota 2 like the other bot does). With those issues in mind, here is how I imagine requesting a coupon working:

Gabe wants to buy Half-Life 3, but it's too expensive at full price so he would like to have a coupon. Gabe checks Coupon Bot's inventory and sees a coupon for 33% off (alternatively, since there could end up being a lot of coupons, I might end up making it so that Gabe can go to a pretty looking website with a nice big sortable, searchable list of games that the bot has coupons for; it might look vaguely like this). He thinks, "Ooh, perfect; I love the number 3," so he adds the bot as a friend