I struggled to find it any cheaper than that to be honest, the US ones work out more once you add on the £17 Delivery and £80 Import charge.
2nd hand you may be lucky to pick one up on here for a good price or it depends if you get a bidding war on ebay.
I watched a couple on there around March time and one went for £240 and a second one (which was an battered looking older model module and said it had been 'in the back of a draw') went for £260!
It seems like they resell pretty well, so I decided for the sake of £30 to get brand new for the peace of mind and to have it in warranty.. I haven't had to use Mods4cars support but I've heard they're excellent!