Jees....
Ive just quoted Dave EscCos for exactly that, a 400bhp capable engine.... It was over 6K less than that and included VAT!!

However it was engine build only and to be fair some folks quote gearboxes and brakes etc in with their conversion costs

Id say in general costs have dropped dramatically in the YB game, but tuning in general will always be an expensive game in the uk due to teh relatively small target audience we all have. Its teh same in any bespoke industry, the less potential customers there are, the more each item must cost to sustain its vendors.