I know the owner of the OVRLND that is pictured on the white Tundra. Pretty sure the only *option* he did was the barn doors. With tax, it was around 12k. Without a mattress.
He had a FWC prior (not sure which model or how well equipped) but he felt it was too heavy for the Tundra in areas here in AZ/UT/MX that he likes to go. Plus, he's 6'4" so he can actually stand up now inside and keep his expensive mountain bikes protected somewhat from theft.
I was fairly interested, especially since they are built in Flagstaff, until I found out the price. Heck of a lot for an unfinished shell IMHO.
If FWC does bring something like this to market, my guess would be 8-10k