The perfect storm is rattling New Zealand's wine industry, once regarded as an agricultural cash cow. Latest figures from Realestate.co.nz reveal 96 vineyards are currently for sale, with the average selling time being nine months.But real estate agents estimate the figure could be closer to 150. Consecutive years of frosts in early 2000 led to lower harvests but with higher demand and top prices for sauvignon blanc grapes.But the bubble burst in 2008 when the huge proliferation of vineyards and great weather meant a huge glut of wine, and prices tumbled.