According to the Japanese magazine, the packs will be rolled out on a weekly basis starting next week, which is when the game ships to Japanese stores. There will be five weekly packs, each running 400 yen on the PS3 or 320 points on the 360... which actually works out to around 473 yen right now.
Price discrepancy aside, the real kicker is that after five weeks of costumes--taking us up to March 12--there's an "All-in-Pack" listed for 1200 yen/1,000 MS points on April 30. Assuming that this pack contains the costumes found in all the previous packs, players who decide they can live without the costumes on a weekly basis get a significant discount. Shouldn't the die-hard players who demand maximum clothesosity in their fighting games get the discount instead of getting hit up for a few bucks every week for over a month?
Of course, there's still no firm details on what will be in each costume pack yet, and I'd guess that the prices for this stuff will even out between the two platforms before they're released here in the States. We'll have to wait and see how Capcom plays it, but the sad fact is that I'll probably buy as many costumes as they sell, and I'll buy them as quickly as they'll release them.