To clarify my opinion: I think that the manufacturers that have been around for a long time and have a good name (e.g. B&M) may be able to sell their coasters slightly more expensive than other manufacturers, because theme parks will probably be ready to pay a bit more if they are sure that they will get a good reliable ride. But I'm talking about slight differences. If Gerst built a coaster similar to a B&M one, it would still be really expensive, but probably not as expensive as if B&M did it. Anyway, Gerstlauer doesn't tend to build big rides, because even if they would be cheaper, they probably couldn't compete with B&M, Intamin and the other bigger manufacturers. That's why they specialized on medium sized rides, getting as much fun as possible while using as little resources as possible. (For example Karacho is a really funny coaster, on just ~700 meters of track.). That makes the rides cheaper of corse, fitting better into the budget of smaller parks.
I also believe that (keeping our examples) B&M and Gerstlauer are not direct competitors, since B&M wouldn't want to build a ride for Gerstlauer's prices and they probably wouldn't want to build such small rides for image reasons, and Gerstlauer won't get a contract for a B&M sized coaster, because parks would want to put such a big investment into the hands of someone who has proven themselves many times.
Disclaimer: This is purely based on my perception. Feel free to argue for and against my views (as long as you stay polite, some of the posts here already had a negative, sarcastic touch which I didn't like). I have no facts to prove my opinion, but I'm ready to change it if someone can deliver facts accordingly. (Parallels in the car industry and other "metaphors" are no facts.)
I just wanted to clarify my opinion because my post kinda started this whole discussion.