We're looking to plan a trip to Europe (we live in the US), and I have been monitoring Kayak, et al. First thing I noticed is that prices jump up and down, even within hours. Last week for a few hours I found tickets for $800, but now they are back to $1200-$1400. I wish I booked then

But what surprised me the most that the prices for the same route, same date but starting in Europe ar way lower than when starting in the US. Any idea why this is?

Supply and demand.

Are all priced in the same currency. A 100 euro tickets looks cheaper than a 140 dollar ticket. I am surprised you passed up an $800 ticket - assume you thought it would go lower.

Works the same way here in Australia. Flying from Perth to Singapore is always more expensive than flying from Singapore to Perth, same airline, same travel dates. For the dates I just checked, it's a AUD $262 difference, but I've paid as much as AUD $400 more. I always thought it had something to do with Australian taxes, but the supply and demand theory works well too considering how isolated Perth is in the scheme of things.

I really wish I got that $800 ticket, but I didn't have my CC with me when I saw that. The next day it was gone.

Could the Olympics drive the price up too? Even though that is 6 weeks later, and we're not going to London?

And then suddenly, BOOM, the prices to one of the possible destinations dropped back to the low $800 per ticket. Gotcha!

always try switching to a different computer / wifi connection - I find that I get stuck on a price sometimes and as soon as I aswitch to a different IP address the price drops.....