Thanks for all your replies.
If I look at the Stansted Express main website and select 2 express class return tickets for this Friday, from Tottenham Hale to Stansted, the price is £55.00 (£59 from Liverpool St).
If you go to
Ryanair's subsite on the stanstedexpress.com domain, Liverpool St - Stansted return is £43.20. There is no Tottenham Hale - Stansted option on that site. You also don't need to have purchased a ticket with Ryanair to use that site.
Unless I'm missing something, going to a different page on the same domain of the operator can save you a little less than £16.00.
I love trains (I'm a member of this site!) but I think the prices in the UK (I'm not from here) are a rip-off. I would never have paid £59.00 for a trip to the airport; that costs more than my plane ticket!
I was looking to take my partner to Edinburgh. I would love to have taken a train there. I check the fares on East Coast's website and wow! An April 6, 2012 weekend return ticket for only £390! (I hope I missing something here)
In the end, I only chose the £43 fare over the bus only because it was "only" a £15 difference and it satisfies my enthusiasm for rail.