This is where we got ours. I'm not sure if you can buy in small quantities for some of the items though. Perhaps you could find a couple of families who wanted to go in a box of catheters? That's what we did.
Also, I don't know what you're using, but my ex was a vet, and laughed her head off when she saw the fancy tomcat catheters I had been ordering online (for $$$). Turns out, there are the exact same tomcat catheters vets use to, well, unblock tomcats. So, if you know someone who works at a vets office, you could try to snag/buy some that way. I think the time I got pregnant was actually with one from her office.