I'm like you, I usually just set some general criteria and see what comes up that's a good deal. For my latest purchase I was just cruising craigslist by manual transmissions, looking for something fun, and ended up with a good deal on a 6 speed Xterra 4x4.

I've cross shopped a restored salvage title Volvo 850r wagon and a clean low mile Crown Vic detectives car, with the criteria being something under 5k (in 2011) that could move me and most of my stuff across the country.

I've also ended up with gen 1 & 2 SHOs and an Eagle Talon TSI this way.

I think I know what I want for my next car, but old habits die hard. "I want x, but for the same money I am seeing y, and for a bit more I could get z". Automotive wanderlust.