That comment was made as an exaggeration, It's not 6k just to rebuild But it's at least 6k including the original cost of the vehicle. You've only got to look at the cost of good second hand panels to see where the money has gone. And £1200 on a chassis. You're doing a rebuild your self so I'm sure you know all the little bits soon add up.
I've had a few orders with lr direct with what seemed to be made up of nuts, bolts, washers, screws, seals and gaskets, bearings etc... and its £250
I certainly do know how the bits mount up. I've spent 3K already and still have a long way to go
Your Landy is in better condition than mine, but I could still imagine racking up a big spend. Doing your own painting will help massively. I might end up being forced in to doing that myself.