Re: aiki koshita
Unless you are buying it from another person, I don't see how you are going to get an aiki koshita from bujin (they closed ::sniffle). I had strongly considered getting an aiki version because I hear it is great for ukemi, but I didn't think it would work well for iaido.
If you aren't looking at them at bujin, may I ask where you have found another supplier that does? I would like to get one in the future.