Gaz fuel burn is a little less than 2.5kg per minute flat out - don't know what that is in gals/hr.
A freind has just bought a civvy Gaz for £180K'ish. Can carry 5 without restrictions so makes £145K for an ex-mil '2-seater' seem expensive.
Also, watch out for component times. A new engine / MRH are serious £££.
However, you don't usually find Ferrari owners complaining about fuel economy or servicing costs! In helicopter terms, the Gaz definitely performs like a Ferrari!