A dispenser has a housing, and a variable-volume storage chamber formed within the housing and defining a substantially fluid-tight seal between the chamber and exterior of the housing for storing a substance to be dispensed. A piston is mounted within the housing, and a one-way valve is mounted within the housing and coupled in fluid communication with the variable-volume storage chamber. A compression chamber is coupled in fluid communication between the piston and one-way valve, and at least one of the piston and valve is manually depressible relative to the other between (i) a first position in which the piston is located at least partially outside of the compression chamber for permitting substance to flow from the variable-volume storage chamber into the compression chamber, and (ii) a second position in which the piston is located at least partially within the compression chamber for pressurizing substance within the compression chamber above a valve opening pressure and, in turn, dispensing substance through the one-way valve and out of the dispenser.