One of the cheapest i found if you're in the ex-London is to take IB via madrid to valencia or seville - around £400 for 160 tp (£2.5/tp). in the states, i'll be doing mia>las via lax rtn in P for about $1,100 or £665 for 480 tp (180+60+60+180). that's £1.39/tp, which i suppose isn't too bad, except of course that one is flying AA