@saiyoucho:
In regards to getting the game at Comiket, you have to plan a lot better than how I think you're going about it.
I went to last year's Summer Comiket and was hoping in the offchance to get a copy of SA and I failed badly. I actually never found ZUN's booth (though I didn't explicitly try once I got in). The halls are huge and while the map in the catalog is pretty accurate, navigating through the rows and rows of tables takes some getting used to. Drawing up a floor plan and path is something I would definitely do the next time. And the talk I heard afterwards was that ZUN's booth was out of stock after about 3 hours and I didn't even get inside the con till after noon. (I think I stood in one spot outside for 45 minutes). My general impression is that if you're not waiting at the con within the first hour of trains starting up again in the morning, you're not getting the game.
In general though, I've learned the optimal way to do Comiket is to indeed get the limited merchandise goodies. Prioritize things on desire, rarity, what time you're able to go and how many people you are attending with who will also stand in lines for you. Try to be aware of what's available ahead of time. I missed out on a limited Touhou grab bag (oh the precious Yuyuko fan I missed out on) that Toranoana was selling because I missed the fact that there were commercial booths upstairs and a few of them sold Touhou stuff. Depending on the items, you'll probably make under 10 purchases the entire day and spend the bulk of the day in line unless you finish waiting in line and just wander the hall afterwards. Budget yourself too, or if you have a relatively high budget, just buy it. Unless you want to get something signed by the artist, you won't need to buy most doujin comics or music at Comiket. Stop by Akiba's Toranoana or other shops a few days after and snatch up the bulk of the recently released doujins there for a few 100 more yen markup.