Travel from Heathrow to London city is shockingly expensive using the Heathrow Express. It IS a great and slick train with WiFi but 34 GBP ($55) is steep.
The slower option, Heathrow Connect, will set you back GBP 9.90 for the one-way ride to Paddington.
But Heathrow Express has a promotion that allows British Airways Executive Members (membership is free if you are not a member) to use the train's business class for free when booking a regular ticket.
When you price out tickets normally you will see this (prices are the same online and offline):
The special business class/first class pricing is only available online and will look like this:
This makes spending $55 on airport transfer a bit easier to bear (at least for me).