If you are looking for a good fukuro shinai, your best bet is to order it directly from the Jinenkan Honbu website:  Honbu Equipment Page.  These are by far the best made shinai for actual hard training.  If you try to use a kendo shinai you will either severely injure your training partner or you won't be able to train with the intensity needed and will develop bad habits of "going too easy" on your opponent.  Note these shinai start out white, like the nice new shoto at the bottom of the picture.  After years of use and the addition of many gallons of sweat, a little blood, and some leather care products it will mellow to look more like the daito at the top of the picture.