Si, 2.5 bar is a powerful pump but will give you an awesome shower. I had a 1.5 bar pump fitted at my last house and it was fabulous. Money sounds reasonable to me, although the fitting may be a bit dear as they aren't too complex. Have a call with City Plumbing (branches all over South Wales). If you can get a plumber to order it for you you will get a much better trade discount, even if you pay the suppliers yourself. Shouldn't this have been sorted when you had the shower fitted? (sorry to state the bleedin' obvious!) Assuming the shower uses the hot water from your tank i.e. is not an electric shower, then a pump was always likely as the gravity fed pressure is not great on most systems. Hope this helps!
Do get a pump though - so nice to have a power shower....
Do get a pump though - so nice to have a power shower....