The cheapest Mellow Corn whisky is Mellow Corn (50% ABV, 70cl), at £29.50 from Master of Malt. That is £34.45 delivered to the UK mainland for one bottle.
What is corn whiskey?
A US whiskey made from a mash of at least 80% corn and distilled at no more than 160 proof. It must be bottled at 40% ABV or more and may contain colouring or flavouring unless it is labelled “straight”.