To be honest I don't think there is. Airline pricing is deliberately a dark art - after all if we knew when fares were going up or down we'd never pay top whack and they'd make much less money.
On T-330 you might find they don't release the cheapest fares straight away in the hope of fleecing the "worryworts" who insist on booking on day one. And obviously as a flight fills up, the cheaper buckets sell out so the lowest priced ticket goes up.
Otherwise the airlines use complicated algorithms to work out fares which can fluctuate day to day or even hour by hour, based on factors like their costs, past and likely future demand and what the competition's charging.
Essentially the old V-Flyer rule applies: if you see a price you're happy with, go for it and don't check back. Chances are the person sitting next to you will have paid less - that's airline fares for you.
