Bit of a different post, non-D&D related. Thought I would list here some of the better model shops in Akihabara for anime/manga/pop-culture. Google will give you a list which are mostly hobby shops which is not what you want (for example TamTam and Animate).
Kotobokukiya, is right across from Super Potato. Mostly video game related models and merch. Its well-organised store and they also do duty-free. All new models/merch. Map.
Liberty Anime is along the main road of Akihabara. It’s a one-floor store that has both current models and second-hand models for sale. It’s across the street from the California Grill. Map.
Volks Inc is a second-hand store and has the largest collection of models out of those listed here. Just a note that if you see models displayed in glass cases these are second-hand models. You will get them much cheaper than the original boxed versions but you won’t get any box. Map.
All these places accept credit card as well.
Finally, Akihabara Radio City has mostly boxed models mixed in with the tech stuff. The new stuff is expensive (for example an unopened model of Mythra from Xenoblade was going for 56,000 yen). Map.