Ikebukuro
I find gachagachas more appealing than, say, big ol’ $100 garage-kits because they’re, oh, about 1/50 the price, you actually get to assemble them yourself, and if you are lucky enough to find them while they’re still in the capsule machines you get to play the collecting game. Plastic models also seem like a great value to me because for only 2000-3000 yen you get hours of enjoyment and relaxation, and when you’re done you have something you made yourself that also reflects your loyalty to a series.