Here’s a tip for keeping fares down when searching for and booking flights on the internet:
Keep all the pages you visit open until you have selected a particular flight, paid and received the confirmation. Only then, close the pages with the flight options you didn’t choose. Airlines have software which keeps track of searches and remembers your IP. That means they know you were interested in a particular flight and can put the price up next time you visit the page. Keeping the page open will avoid you paying more unnecessarily.
If you can’t do this, delete your browsing history when you close a page, which has the same effect.