Just been round to my local annodising plant!
Talked to the guy there and had a look at some bits he had just done,blue and red which looked a good match for tuf neck stems etc.
He said 40 quid minimum price for 1 colour.
You would need to do a few parts for it to be economical.
Any old ano has to be stripped by them first.
They cant do anything made from 7075 ali because of zinc content,something to be aware of(maybe other places can do it).
Also enquired about chemical blackening but he cant do chromoly(would look good on one piece cranks etc) this is quite cheap to do i think.May get some bits done and show you the results!