www.yesasia.com <--- THE BEST FOR BMIIDX AND GF/DM
www.himeya.com <--- Popn' and the controller are sold here
You're probably saying, which mix should I get?
For IIDX, 6th style. You'll have a hard time in the beginning but when you get better it'll be REALLY worth it.
For Pop'n, 7th. It has a MASSIVE songlist and lots of good ones.
GF/DM, just get the newest one.
"Which controller should I get?"
For IIDX, the official konami one. This is the best IIDX controller you'll get next to an arcade style controller.
For Popn' the arcade one, but it's $325 so get the cheaper 60$ one.
For GF/DM... the official konami ones.
"How can I play these?"
1) Japanese ps2.
www.yesasia.com I did this because I'm too paranoid to mod my ps2.
2)
www.ps2case.com <-- This GREAT reviews. The case itself is 30$ and lets you play jp games with ease.
3) Modding your ps2. Hahahahahahaaaaaaaaaaaaaaaaaaa........ wow, that's funny, hope you have a bunch of money for backup ps2s.