Healer's freind 1 is an absolute must. Its too cheap and too good not to have it.
Unless you are wiz/sorc, its just very disrespectfull not to have it.
Its also just plain stupid not to get it. Its alot better then having 15% more hit points.
Getting healed more and faster has alot more advantages for yourself other then just saving your cleric's mana.
I personally have healer's friend 2, and I wear a +10% item when I go into tank mode with a cleric behind me.
Healer's friend 3 just costs too much.