[Si Coe]

As many others have said, I don't think they've got more expensive at all. What has happened though is that prices have got extremely variable.

Lets take Durango - When they first brought the DEX410 out it was the most expensive car on the market at £400 or thereabouts. Today you can pick up a V4 for £270, and the 410R v3 cost £180 when they stopped selling it. One basic design but wildly different costs.
Of course the first cars had a lot more machined alloy and a lot less polymer parts but overall reliability, strength and performance has improved. Durango realised you could make essentially the same car for a lot less.

It cost them as many customers as it made.

You can make a competitive buggy for very little, but even an 'expensive' buggy isn't. Compared to so many other hobbies £300-400 is not a big deal. You can get a 210V2 for £160, or an RB6 for twice that. Most club racers won't really notice the difference (if they claim to its normally that they just a a better setup for the preferred one) but lets be honest who really wants the 'budget' Durango when the 'luxury' Kyosho is still affordable?

And thats the point. Companies sell £300+ cars because people buy £300+ cars. Willingly. A more expensive car has to be better, it just has to be, so we have to have the best we can afford.