I am in total agreement with these guys. Your medic can go a lot farther with a lot less compared to stims of any kind. Medics can heal 40 - 90 HP (depending on skill) at a time, and without the point-loss problems of super and ultra stims.
Concentrate on buying the doctors bags, paramedic kits and first aid kits whenever you can. Distribute stims around the party for use in close situations (like if you are about to die), but other than that rely on the medic.
And just check out all the merchants in random encounters and Kerr at the base. Between that, healing powder and looting bodies you should have no trouble finding healing supplies.