When they were to play in July it was because of them playing Sonisphere. I would think their own full tour would cost more therefore influencing ticket prices. 25 quid is great value with the fact Alcest are playing too.
I think DME are very fair in their ticket pricing and I would say they often take a hit on poorly attended gigs. Thank God DME exists as they have brought some savage bands here. Wouldnt want to be waiting on MCD to bring a somewhat decent band over