@excelsior - congratulations on reaching 70 units - a real milestone achievement :)
Donor myself, though only in the low 20s.
It is worth remembering that in the UK, all blood donations come from unpaid volunteers, and that roughly 2 million units of blood are collected from just 1,5 million donors. It would help things enormously if more people volunteered to donate....
http://www.blood.co.uk/