$375 in August 28, 2002 when I saw it at an @Last booth at a trade show at the Javits Center in New York City (can’t remember if it was MacWorld Expo or an AEC tradeshow). As mentioned in this other thread,
I had been using Alias (Sketchtech) Upfront for 9 years prior, and it was becoming apparent that further development wasn’t going to happen any more, so I was looking for a replacement. SU looked so similar to Upfront, I thought it was basically a knock-off. I had just caved and bought ArchiCAD the month before, and wished I had seen SU first. I do remember being just about sold already when someone demonstrated moving a section cut through a model in real time, and that sealed the deal for me.
At the time, the bulk of my work was mostly 2D in PowerCADD, though it had perspective tools as a part of Wild Tools (very old example page here), and I just used SketchUp for exterior shells and perspective views. Gradually over time SU grew to be a greater and greater percentage of the work flow untill now where it’s the majority, but PC still comes into play when I need it.