Your best bet would be to follow the link above to the ever helpful UK RV builders site. There are a load of RV-9 builders there who will help you with the true costings etc.
There isn't a UK importer, everything is done through the factory and it isn't really a problem. Harry Hopkins (Avery tools and RV-4 builder/pilot) provides (provided!) cover at the Rallys of old.
As for what you build. Many RV builders have gone and built another (or more) - you don't do that if the product isn't any good. There's now close to 5000 RVs flying around the world and 134 flying in the UK. You can't get a better machine for the UK - the combination of take-off/climb/cruise and landing performance (both grass and hard) is hard to beat.
Also have a look at:
http://www.rvuk.co.uk/index.htm