The difference in usefulness between a +1 and a +9 healing kit is not proportional to the effort involved in crafting them.
Not that it comes up often but Bandages cure poison and disease. Healing potions do not.
Drizzlin: As someone who can't make healing potions, I find buying healer's kits an extremely good deal. At level 19, I'm getting 35 hit points a shot out of them.