I just booked a ticket through National Express and spotted a way to get cheaper tickets (half price or less) depending on where you’re going. They currently offer what they call “funfare” prices on certain routes. The one I looked at was Cambridge to London. However, it’s quicker to get a bus to Stratford (halfway roughly) then then catch a tube the rest of the way.
However, Cambridge to London qualifies for a funfare ticket from £4 to £6 (normally £10 upwards). Cambridge to Stratford is £10.30 with no cheap options. What’s important, though, is that you can purchase the longer distance ticket – for less money – and hop off the bus early. This is allowed by the terms and conditions as long as you tell the driver when boarding to ensure your luggage is stowed conveniently.
So when booking a National Express ticket, if you’re planning to disembark partway along a major route then you should check the price for the full route and see if it’s cheaper than the segment you’re doing.
This correct at time of writing. I’m sure their offers change all the time.