Those kinds of archi shots are mostly rendererd in VRay or Maxwell, running under MAX. Total investment would be several thousand $$. The second most used is mentalray, running under Maya, XSI or MAX. Cheapest of these would be XSI foundation for about $500 which comes with one seat of mentalray. Lightwave can work also, with fPrime about $2k..

Of these, the best one for poser chars themselves is probably mentalray cause its skin shaders are currently unsurpassed by any other app. It is quite hard to learn though, esp if you dont like math.

And yes i agree that Indigo shows a lot of promise, hope they keep adding features to it so it can really take on the big boys of the industry.

EDIT : oh and keep in mind that you can get very nice looking renders even without expensive renderers. But you will have to learn to light properly. You may be surprised to learn that a lot of the shots you see in big budget blockbusters make no use of raytraced reflections, raytraced shadows, IBL or other advanced features. Just very experienced lighting artists.