[chrisseaton]

> I wonder if a plane was packed with all first class seats how expensive the tickets would be.

It's pretty normal to have all lie-flat business/first-class flights between major business centres such as New York and London. You wouldn't know about them unless you were booking a first-class ticket in the first place, so they're not very visible.

I think the prices are the same as normal? Otherwise nobody would use them, of course.