I would also recommend checking the prices frequently (like once a week) on several different places, like itasoftware.com, kayak.com, etc. That way you know what a 'normal' price is. Then, set a price you would be happy with. If the normal price is $1500, would $1100 make you happy?

then, when it actually does hit $1100, don't quibble, just buy - because it might be gone in an hour.

I went to Scotland this June/July, and started looking at prices in November. End of January came around, and the normal $1200 prices dropped to $800 one morning on Orbitz. I bought (that's $800 including taxes). It saved our group of 6 a lot of cash :) Of course, the service on US Air left much to be desired, but it got us there and back.

Good advice, GreenDragon.

I personally use Travelzoo to do my regular searches. All it does is crawl airline and booking sites (including all the legacy carriers, plus Kayak, Orbitz and whatnot) and star the ones with the best fares for your route, but over the past few months alone, I've found ORD-SJO r/t on AA for $400 there and ORD-PRG r/t on LH for $800 (both including taxes and fees). I've found some great deals there over the years.