You asking if three rail track is more expensive than 2 rail track?
Or are you asking if the Marklin three rail system is more expensive than the more common 2 rail system?( common outside of Germany that is for the most part)
Or do you mean C track vs. K track?

I believe that the price of C track is the same or at least very similar between Marklin and Trix.
C track vs. K track ; K track is initially cheaper but it naturally has to be ballasted, so it works out to be the same per length.
It comes down to personal choice; speed and ease of set- up or slightly more realism.

As for Marklin vs 2 rail (roco, fleishmann, etc.) well there is an essay! So in 2 sentences.
I think that Marklin has the best balance between detail, robustness and cost and can run on small radii.
Others are good at some of the other aforementioned qualities.
It depends on what your focus is? Ease of running, attention to detail, durability, running train or just collections? That is for you to decide.

Hi.

C track in either Marklin or Trix brands is the same price. I happen to use both.

Here is an example from the web site at http://www.modellbahnecke.de/shop/en/Model-railroad/Trix/H0-C-Track/3/

Marklin C-Gleis Gegenbogen zu 24711/12
Art.No.:24912
N00 Scale: H0

Euro 5.49


Trix C-Gleis Gegenbogen zu 62711/712
Art.No.:62912

Euro 5.49

regards
Kimball

Hi!
AFAIK Trix C track is made with both rails connected - connection will be cut before it's shipped. Less material, but one extra step vs. Märklin C track.

I might be off topic, but did you acutally work with K-track¿?
It´s not that it is so much more realistic when you ballast it yourself. (Although some people complain about the high profile rail too...) -I find that the hugest advantage lies in the GEOMETRY;
The slim swtiches are excellent, and occupies a LOT LESS real estate than C-track. No strange 24071 peices.
You get a slim DKW that almost works.
And... the best of all; Flex-track... Priceless!