If you follow the same mini blogs I do, you’ll know that converting nifty fish tanks to modern dollhouses is not a new idea. The Call of the Small blog did just that with the Fish Hotel from SFMOMA. (PS do also check out Call Small’s blog and her Flickr for more modern eye candy!)
As for the Archiquarium, it is currently in production to be sold sometime in the future. I searched around, but was not able to find any kind of pricing information. My guess is that it will be expensive, but probably not more so than the cost of an actual modern dollhouse (e.g. $300+).