I spoke to several of the Tepui reps, but I believe it was John (could be way off) that gave me the price estimate. We actually spent quite a while comparing it to current offerings by other companies. All the reps were very honest in that this was prototype #1 and that there would be changes to the final product. No one could even give me accurate dimensions.
While I agree that the AluCab model is on the heavy end, anyone looking to add an RTT plus additional gear on top of it probably isn't that weight conscious. Plus I believe there are Eezi Awn models that approach that weight, so it's not anything others haven't done in the past. Personally, I try to minimize weight carried up high at all times, and would never consider adding more weight strapped to the top of my RTT.