(applies to all travel agents, I'm just using FC as an example)
Flight Centre - the world wide travel agent, often boasts "lowest prices guaranteed". I've had trouble getting them to actually hold to this in the past, but generally if you can prove you can get the price elsewhere, like a print out of say, AirNZ's website with a price, they'll match or beat it.
Does anyone know if they'd be willing or able to match ITA's Matrix site? It gives prices, but doesn't always indicate WHERE those prices are available. If you took those prices and flight details along to a travel agent, like Flight Centre, are they able to find the flights for the same price, given all the flight details, assuming the flight is actually still available?