I did a little poking around on Orbitz.com, Travelocity.com, Priceline.com, etc today. It looks like there are quite a few flights from Detroit to LA for less than $300 round trip. Not that $300 is chump change, but having flown to Detroit a few times now I can say this is way better than what we have spent in the past.
It looks like Travelocity has the best prices. Theirs are around $250. Most of the flights are on US Airways. I checked pricing through the US Airways site but to buy that way is more expensive so I would go with a Travelocity instead.
I hope this helps some of you!