New Delhi, Sept. 17 -- Retail onion prices are refusing to budge from the Rs.50-per-kg mark despite government intervention, with supply constraints expected to keep the market firm through September and October. Fresh kharif arrivals, delayed by the late monsoon, are expected to bring some relief from November, experts said. The all-India average retail price of onion stood at Rs.53.84/kg on September 16, against Rs.27.71/kg a year earlier, according to data from the Department of Consumer Affairs. That means onions are now 94% more expensive than a year ago. The average wholesale price was Rs.45.65/kg on Wednesday, more than double the Rs.21.54/kg recorded a year ago. The government has been releasing onions from its price-stabilisation b...