Looking to fly GUM-NRT-GUM in late January/early Feb 2014 as cheaply as possible. UA and DL seem to match either other to the dollar on this route and having a look at random dates across this year (not sure if my dates are correctly loaded yet being so far out), it looks like the best standard price is around US$515 pp return.

This seems reasonably expensive given the length of the flight. Is this the best price I'm likely to see? Does the route ever go on sale? Are there budget options?