Accurate Armour produce a kit of the Type-A mini sub. Resin and too expensive for my taste. £149.99 (about $284) + carriage.

http://www.accurate-armour.com/ShowProduct.cfm?manufacturer=0&category=13&subcategory=27&product=1864

These are all WWII subjects:

Fine Mold's 1/72 Type A Japanese WWII Mini-Submarine

Kora 1/72 Japanese Kaiten Type I Suicide Submarine

Kora 1/72 Japanese Kaiten Type II/IV Suicide Submarine

Kora 1/72 Japanese Shinkai Suicide Submarine

Kora 1/72 Japanese Kairyu Submarine

Kora 1/72 Japanese U-Kanamono Submarine

Kora 1/72 Japanese Type A Submarine