Not sure how big a thing you're trying to measure. I recently bought one of these: http://www.ebay.com.au/itm/Ultrasonic-Laser-Distance-Length-… for ~ $12.30 delivered, for measuring room sizes when we inspect houses (don't get me started on the work of fiction that is some floor plans). It's quite large (would fill a large pocket). Seems accurate to within a centimetre or less (which is fine for measuring rooms). Not sure if that's the type of thing/scale/error-tolerance/price you're looking for.
Not sure how big a thing you're trying to measure. I recently bought one of these: http://www.ebay.com.au/itm/Ultrasonic-Laser-Distance-Length-… for ~ $12.30 delivered, for measuring room sizes when we inspect houses (don't get me started on the work of fiction that is some floor plans). It's quite large (would fill a large pocket). Seems accurate to within a centimetre or less (which is fine for measuring rooms). Not sure if that's the type of thing/scale/error-tolerance/price you're looking for.