I'm genuinely curious why some people are bothered by the shutter sound. Personally it's not an issue for me and it doesn't bother me.
I don't take upskirt pics, but I can imagine some situations were I don't want to make noise. Like, think food pics in a fancy restaurant. Or just any situation you don't want to get attention. Price is very attractive though: http://www.iphone-worldwide.com/
I wonder, can't you simply flash it to an official non-JP ROM version? No Jailbreak, original Apple ROM. (no idea that's even possible, probably not I guess)