This is a very late reply but I'll write it for future reference;
If in LA you might try the The Center for Film & Television Design at the Art Directors Guild Building in Studio City.
Another option is to do a Library Search; large libraries often have a host of strange items you wouldn't expect (I remember coming across some blueprints from Star Wars at the British Library that kept me enthrawled for days).
Also a good resource it to check is fansites of the film you're looking for (where the dedicated fans have put in the hard work locating images so you don't have to), or if you're lucky, the portfolio site of the Production Designer of the film which will often have very good resolution sample images of what they've worked on.
The final option I'd suggest is good ol' eBay. You'd have to be having a very lucky day to get the exact film you want, but construction drawings turn up suprisingly often from more recent films (usually and unsuprisingly they've been used and may have handwritten notes or amendments scrawled on them). As I've said, the closer the film is to its release the better chance of finding some drawings you want (but even then the chances of it being the set you're looking for isn't high, so remember to cross your fingers before hitting 'search').
Well that's all I can suggest, I hope it may help someone.
