Do I need Adobe Livecycle Reader Extension ES2 to allow the 2D barcode function in the Adobe Reader (it seem to function in Adobe Pro w/o any additional software, but not in the Reader). And if so what would be the price of the extension acqusition?
Yes. The 2D barcode right is required for 2D barcodes to function in Adobe Reader. You would be best to open a discussion with your Adobe Sales rep on cost for Reader Extensions Server.