If you have a smart phone with mobile email, create an account on If This Then That. I basically used the website to set up a trigger that sends me an email anytime a new ad containing the word "Weber" in the title is posted. Almost scored a new gas assist performer a few weeks ago for $50 but missed it by about 5 minutes. Had I not received the email telling me about the posting, I would have never known the ad was even posted. "Weber" is the only search that I get email for as to avoid getting too many CL emails.
On top of that, I also search for bbq, smoker, charcoal, grill (title only), barbeque, and misspellings of all of those. Mostly though, it comes down to being in the right place at the right time which makes up half of the fun of it.
18.5" OTS, 22.5" OTG, CB Silver(Rip), Vintage Coleman Bullet, Pit Barrel, UDS