when bilding an ultima do you have to buy all the parts from them or do they allow you to manufacture your own? its seems a bit steep for a set front wishbones £544 when they look as if they could be easily made!

You can buy pretty much any part individually from Ultima.

Up to you if you want to mix and match, but bear in mind that you might lose a bit of the Ultima value if you start buggering about with DIY wishbones.