I have just bought the following bike and I want advice on rotors, the bike currently has Shimano Deore Disc and I have a set of spare wheels and want to put the correct rotors on them, I don't want to pay the earth as this is the first bike I have run with dics so you could say I'm new to this.

What do you recommend???

OK pics didn't work, model of bike is "CORRATEC X-Vert EXPERT" google it.

take the rotors off the existing wheels and put them on the spare wheels? or am i missing something?

No you are not I have wheel for the road and wheels for the off road.

As long as the diamter (140mm / 160mm / 180mm / 185mm / 203mm) is the same you can use any brand.