There could be a few things that might affect the price ;
1. The booking/fare class you saw earlier may not be available now - this is the most common reason why one would see a higher fare
2. Most of the browsers use Cookies or some sort of tracking mechanism - this will tell the airline website that you are interested in the ticket and they increase the price every now and then to give a sense that the price is increasing and there by putting pressure on you to lock in the fare and book the ticket
3. if you for instance, tried the same search on a different browser, or, use inPrivate or inCognito mode browsing on IE or Chrome respectively, chances are you might see a different pricing
I'd suggest, if you've got a TA, talk to them .. actually a few of them and see who gives you competitive pricing.
The thing with TA's is that most of the airlines sell tickets from low fare buckets to the TA's and TA's are expected to fill/sell them ... one of the reasons why you can find a cheaper ticket with a TA than booking directly with the airline.
You might also consider looking into ITA-Matrix
Matrix - ITA Software by Google This website lists all possible fare, airline combinations and you can take your pick. You won't be able to book directly using ITA, so you need to use a TA or you can use
BookWithMatrix - Book flight itineraries from ITA Matrix to book the itinerary found on ITA Matrix.
Hope this helps
Cheers,
Ade