Well you can buy a new X-Box now for about £99. Games new would be about £20 each, and 3 controllers new (- one that comes with it) would be about £25 for two.
So, this comes to £185 new with the 3 games and 3 controllers.
I'd advise in this case since its an old console now and you want to sell it, to ask for about £60-£100 max. Thats jus a guess figure.
How much would you be willing to give it away for? Am I about in the right region?