Not sure if I understand you correctly, but the article states:

    It is generally understood that both parties carry their own costs until the final contracts are signed.

Which is how it's normally done, both sides are interested in a sale/investment/merge so I see no reason why you should expect to get paid for the due diligence process.

The buyer has to analyse all data on which the deal is based, until he is satisfied, which in many cases means hiring experts for that job.