Very good point. One metric I use when investing in a company is...

Very good point. One metric I use when investing in a company is the price to book ratio to determine whether something is cheap or expensive. As NR quite rightly pointed out the sp has no impact on the book value of a company.

For BRK it is
cash can be found in the quarterly $25m
land value you would need to estimate that (I use the NPV of all 21 wells)
non-current assets from the annual report

For those wanting a definition... Price-to-book value (PB) is the ratio of the market value of a company's shares (share price) over its book
value of equity. The book value of equity, in turn, is the value of a company's assets expressed on the balance sheet. The book value is
defined as the difference between the book value of assets and the book value of liabilities.

Investors use the price-to-book value to gauge whether a stock is valued properly. A PB ratio of one means that the stock price is trading in line with
the book value of the company. In other words, the stock price would be considered fairly valued, strictly from a PB standpoint. A company with a high PB ratio could mean the stock price is overvalued, while a company with a lower PB could be undervalued.
Source: Investopedia