At first glance I thought it would be easy to get a pump for this situation. I imagine you'd prefer an ac (vs dc) pump for this application? Shurflo is the first thing that came to mind.
This would probably work, but it's a little more expensive than I had thought it would be at $130. It flows 3.3 GPM which would mean your tank would fill in about 20 something seconds. That seems like a long time to me.
Or
here's another one which should fill your tank in ~12 seconds for about the same price.
Maybe you should get an expected fill time to work with that will help you determine the flow rate of pump you'll need.