That’s a really good deal if it’s for travel right now—in peak season. If it’s for winter, then it’s so-so.

Kayak has a superb multi-destination search.

Oh, that’s November 4th to 18th! Off-peak… so you say it’s not particularly good?

It’s not a bad fare, but not brilliant, either. Kayak turned up $663.

I think all the fares I see online are pretty much the same. Tell me, do all these sites search off one database and pretty much sell exactly the same ones? They all say they are the cheapest when all their prices are similar give or take ten or twenty bucks.
 
Does such a thing as a true ‘sale fare’ website exist where one can find true bargains?

There’s no one site that always gives bargains. So as frustrating as it is, you have to use a variety of sites and tools, and even then, there’s no 100% guarantee of getting the cheapest price.

Some background info:

+ Airlines have sales, but where, when, and how much is up to the airline.
+ Seasons affect transatlantic airfares (highest in summer; lowest in winter, except around Christmas).
+ When one airline has a sale, others often soon match the fare on a competing route.
+ Consolidators (ie, the $663 fare from Cheaptickets) have rates set and usually only go up from that point as seats sell out.

$663 is not bad for this itinerary. With fuel surcharges, and UK air passenger duty, I’m not sure you’ll do better.