Aye, it is a little strange considering how far into the process they are - I was a little drunk and worse for wear when I had heard, I weren't too happy at all.
Concerning 'Money', I've never considered Lynch to be a man motivated by money. I imagine he has enough of it - However, after 16 months of pre-production, he has now decided to leave over budgetary concerns? I don't want to sound like a peppered teabag here, but as much as talent negotiations go, an Auteur like Lynch (And I suppose Frost), would have a budget in place before writing? Of course, this is moot and anyone's guess could be true. They could write, then budget it; just as much as they could budget, write, then budget again, write, budget again... so on and so forth - I'm not clued up at all on finance/budget, but I imagine budgeting and forecasting to be an ongoing process throughout the pre-production phase.
i guess we will find out over the coming months, but for David Lynch to publicly come out and declare in the way that he did is a bit of a strange one. I love Lynch, and it is easy to finger the big bad corporation - But it could be Lynch being an obstinate fucker. Dune, (Different kettle of fish altogether), does prove that he has a volatile relationship with financiers. Whether or not this is just co-incidence, he pretty much dusted his hands with Di Laurentis, argued that he had little artistic control (Final Cut), and then left the production. On Dune, he pretty much didn't see eye-to-eye with his fellow writing team, and in the end, ended up writing the bulk of the script (under intense scrutiny and pressure from Raphael Di Laurentis).
So, while you can't rule anything out, it appears too, that once he makes up his mind, he makes up his mind.