It might be a very good idea to write with budget in mind through the entire script. One scene that is prohibitively expensive or not actually possible to recreate can sink any chances that the script has to make it to film.

I agree, write the hell out of it! If nothing else, it can serve as a great sample and learning experience. I wrote the hell out of a story set in the 19th century and it was optioned by the first place I sent it. Still it may never get made. But it was consistently a top ten finisher in international competitions, and I feel it's the best thing I ever wrote. So write! Write now! Write for ruin and the world's ending!

I had similar experience to Lee M (above) -- I wrote a big WW2 war drama romance bio-pic and it got me mad love in terms of fans abd a major contest showing which then led to an agent, but whenever I ask "so what are the chances" I hear something like "Totally loved it. It'll never get made."

So... write the hell out of it, yes, and use it as an ass-kicking sample, sure.

But don't worry about making time to go Ferrari shopping just yet. ;-)

Ah, the bitterness this topic dredges up for me.

Wrote a period piece last year, my first script. Submitted it to the Nicholls Fellowship contest, placed in the quarterfinals. So a couple of people asked to read it.

One guy from a serious production company emails back with:

"I really enjoyed the read, although period is a bit tough right now. Do you have anything contemporary?"

I did not. It was my first (and thus far) only completed script. Heartbreak.

Great question, as it applies directly to me as well. I'm finishing the polish on the third draft of a period piece. It's based on a book that I got the option rights to and inspired by true events. The topic is something immensely tied to what is going on today.
That being said, I've gotten very positive responses on it so far. But among those, many people have told me the hard truth about the industry right now...no one wants to spend the money on a spec period piece.
Is that going to stop me from trying to sell it? Eff no. The story HAS TO BE TOLD. People must know that this happened in our history. And gosh danget, that's what I believe is gonna sell it. As Scott pointed out, spec period pieces do sell.
Instead of making another cliche rom com and thriller, why doesn't a studio just say screw these two predictable and formulaic films we're about to make...let's just make this one amazing true story!

I'm hoping my period piece does well in the Nicholls and if producers request what contemporary scripts I have, I'm prepared to send them several.