Let me introduce myself I'm Patrick Dumas Marketing VP of REALVIZ.
The price change occured last November with the introduction of IM 3.5. Our main goal was two fold: extend the reach of IM (At $4000 only a small fraction of the potential user population can afford the product) and put the price in line with comparative products. We did also extend its market coverage by providing a MAC OS X version.
We truly believe that IM 3.5 is ideally suited for delivery photorealistic AEC and Engineering models. It's a powerful tool to integrate and communicate your project to your audience.
Cordially
Patrick.