There are still around 16-20 of the exhibited works available for sale. The shots that are currently on the Impossible web-site are not specifically the ones available. If you'd like to know which ones are still for sale you'll need to contact the gallery. You can't choose no. 22 anymore because I've just ordered that one (to my immense surprise my wife liked the first piece I bought, so I quickly bought another one - and a red poster!)
Cost per item is still around the 74550 Yen mark...
None of the exhibition poster are now available anymore - all 10 of them (5 white and 5 red versions) are sold out.