There is a range of definately non-pro drum machines from Yamaha all starting DD I think the DD10 may have been one of the earliest I had a DD5 as thru midi you could trigger any sound from it. In a quick search I have just found a DD35 for £44 and a DD9 for £32 on ebay. They do have a built in speaker - Yamaha quote the DD35 at 10cm. I think they are about the size of a newspaper these are dd-35 from yamaha W: 435mm D: 236mm H: 160mm. You could check these out.