We are interested in purchasing a Voyager, 2004 model second hand with 50k kms on the clock, does anyone know if they have any major mechanical problems, are they difficult and costly to service and maintain?

Definately costly to service and maintain and not cheap to run (on fuel) either. Have a very bad reputation in Britain and plenty of examples about with low miles and knackered engines. They might look good on paper but l would not touch one with a bargepole.