I'm tempted to try this out. But I have a question, how do you handle steam discounts and stuff? For example, for today only Magicka is 75% off, since I'm guessing that you do all this by hand I'd have to guess that you won't update discounted prices, right?

Provide games and packages information
There should be something like ISteamGame to retrieve information about every game available on Steam. One method to get all games and one for detailed information about one game, e.g. appid, name, release date, publisher, achievements, store link, price (depending on the country code) etc. and all subIDs (packages) they're included in.