While searching for something else a few weeks ago I ran across a place that had a selection of hammer drills ranging in price from about $8 to $20. Some had more than minimal amperage ratings. I tried just now to find the place again so I could post a link. I can't find it now, but here a few individual links that illustrate what I was seeing:
jim ___ Have a home upkeep question? Try my help page. It's sort of an alt.home.repair FAQ.