I thought I had this problem,but it turned out to be something else.
The point is that while enqiring about a pump at my local workshop the guy there told me that you can replace just the diaphragm at minimal cost.
Take it apart and remove the rubber,cos it don't work anyway,and see if you can find something similar.
I have also heared of people using several layers of condom/baloon rubber too in an emergency,but these are only urban legends and have not been substantiated in any way.
Do\'nt dream it, do it!