Hey Brad. Sorry about the negative vibes that sometimes take hold in this community. I sometimes think as collectors ourselves, we should all step back and realize that sometimes we're on the search for something we really want, and taking that shot in the dark is really harmless. I've seen more than a few collectors here begging for freaks to help them find something they want at a reasonable price, so I think the snark is quite unwarranted. I'd like to help you. This is what you should do.
1.Go to Expressobeans.com. It's an online community like this one, but it's dedicated mostly to poster art of all kinds.
2.Sign up there
3. Under your profile, you can add the Halloween print to your wanted list and list the price you are willing to pay for it there as well. The site has a database of all posters, and those looking to sell and buy can use it to find each other. I can't say for sure that someone will bite, but it's a good start.(if you need more help or direction with this, just let me know)
4. You can also start a WTB thread in the commerce section there to get more exposure.
That's pretty much it. I'd also throw in that you should try to get a regular version, as it'll probably be much easier. Good luck and I hope you add the Halloween poster to your collection very soon.