We too are using PCA education, and mocking up a variant of a pump seems to confuse the students from real practice. HOwever, I did find a company called Gumbo Medical which sells all kinds of refurb and demo products at a significant savings. Good luck!
Wendy Grbach, MSN,RN,CCRN,CLNC
Curriculum Developer for Simulation Education
UPMC Shadyside School of Nursing