I'm looking at a round trip LAX-ORD October 28-30 and the price increases dramatically when I price it out for two passengers instead of one ($337 round trip for one, $933 for two).

My first thought was that maybe there's only one ticket left in the cheapest fare bucket, so when you add a second passenger that ticket is in a more expensive bucket. But the same thing happens on six different itineraries on those days: $309-$337 for one ticket, $933-$1,573 for two. I can't imagine there's only one ticket left in the cheap fare bucket for each of those itineraries.

The obvious answer seems to be to just buy two separate tickets, but I'm slightly worried that once I buy the first, the price for the second will shoot up.

Would an Expert Flyer account allow me to check the fare buckets and confirm this? I don't have one and it seems like a waste to open one just for one trip.

Any other ideas?