Deedee,
I agree, this is an acute problem for the person who is responsible to look after the stocks and maintain records.
I would suggest that instead of putting a notice on the door you circulate an email to all concerned giving a bit of details so that others know the importance of the step you had taken. I would also suggest that instead of emphasizing the budgetary constraints you should underline the need for streamlining administrative and documentation procedures for the sake of proper record-management.
You can also mention some merits of this exercise just to make them aware that it is mutually beneficial for the organization, staff and you and that it is not just a one-off step but a step towards a whole process through which organization would be able to match in-out stock proceeds, check balance, identify areas of over-use, compare usage with other units, and most importantly plan and place further orders. I hope doing this will negate their criticism.
Also mention that this is a routine practice to deal with stocks everywhere in the world and not an extraordinary thing.
mnaeempk
Naeem in Pakistan 
