You could also use a hammer drill, (something small like a Dewalt) and just use the hammer function.
http://www.nextag.com/SGT91125-Smoothing-Hammer-Air-549598489/prices-html
http://www.nextag.com/Ingersoll-Rand-Air-Hammer-559763035/prices-html
http://praise.en.alibaba.com/product/200124426/203640822/Electric_product/electric_hammer.html
Try this (or something like it)
You could also use a hammer drill, (something small like a Dewalt) and just use the hammer function.
http://www.nextag.com/SGT91125-Smoothing-Hammer-Air-549598489/prices-html
http://www.nextag.com/Ingersoll-Rand-Air-Hammer-559763035/prices-html
http://praise.en.alibaba.com/product/200124426/203640822/Electric_product/electric_hammer.html