You might can find a waterbed pump at a hardware store. (They aren't as popular as they ued to be and are gettign harder to find.) I know PetCo and PetSmart around be carry them as replacement parts. You'll probably also want a longer hose than what you have. Also consider any valves you might want - I'd definitely put a ball valve towards the end for refilling.
Have you checked Craigslist? Sometimes people get out of the hobby and you might be able to pick up a complete one on the cheap.
It is a violation of federal law to use this product in a manner inconsistent with its labelling.