For what its worth, mooching around Charlie's in Newtown on my way to my mid Wales turf I came across 10mm Bosch SDS for ?3.95 if memory serves.
Did 10 holes with it in hard rock on Sunday morning
Also the Drill
SH DeWalt 24v off eBay for about ?100 or a bit less a few years ago now, recently bought a new battery for it off ebay, non genuine DeWalt but genuine Sanyo cells, ?69 inc postage I think, this and drill is what did the 10 holes.