I have been using 'Gold Cruise Control' for around 9 years over various cars / vans. Its one of the first things that I have fitted / swapped after purchase.
I have a model that also allows 3 set speeds to be programmed, in my case, 30, 50 and 60.
While you could fit one yourself I have always took mine back to a chap in Birmingham as they have all the bits and bobs to make sure that I drive away with it working.