Not certain where you are getting the upgrade parts from- but if it is Halfords- Try somewhere else.
Like Velo dog- I recognise one name and that is FSA and they can be improved on for less money. Brooks saddles- but Brooks Grips? And I am in the UK.
My first port of call would be your Local Bike Shop (LBS) to get advice on upgrading. Lots of things there that should not need upgrading and the LBS will have better quality than a Wally Mart store- give better advice and possibly be cheaper.
Failing that- try Wiggle
http://www.wiggle.co.uk/
Or
http://www.evanscycles.com/categorie...ubdept_id=4018