I found the tweet by the sculptor of Goshogun explaining the high price.
https://twitter.com/AlanMoriguchi/status/684965608862040064Basically, it's because of the higher number of paints and it has twice the number of parts than your typical Robot Revo. Along with the usual higher material cost, exchange rate, etc...
Mmm...I bet Yamaguchi could've done it with the normal amount of parts. I hope this becomes a lesson for UC to not let something like this happen again.
Luckly Baikanfu has a simple colour scheme.
Also the alternate colour is based on this.