If I was going at midday I'd get a $80 London to Glasgow ticket. The comparison was as close as possible to the fully flexible any train any time Glasgow/Euston high speed route that sitepodmatt brought up. It's still not as flexible as a UK train - you can't stop off in Phillidelphia for a few hours on your way you New York for example, can you even buy a ticket 5 minutes before the train leaves on that train?

I still don't see his $300 ticket, the only thing I can think of is that he's looking at a return ticket, but then that doubles the price on the Accela.