In reply to mike123:
The main variables are going to be the seat tube, headset and bottom bracket.
Add to which ever of those you need, new cables and hoses, plus faffing with hydraulic fluid etc and any tools that you may need - shouldn't be much as all the bearings are already fitted.
Maybe add a few surpise bits - bent hanger or front mech for example.
As a punt, I'd say around £100 to £150 - could be less though, or more if you need seat post and clamp, headset etc.
One to check would be the length of the head tube on your frame compared to the length of steerer on new forks, especially as they're coming off a smaller bike with presumably a shortr head tube. Could render the whole thing uneconomic.