The cleanest vodka available is New Amsterdam. It is also the cheapest. The other are not even close. New Amsterdam has 0 impurities and 0 additives except for purified water to cut it to 80 proof. Virtually all other vodkas have some type of flavor or anti-flavor additives to cut the burn and any undesired flavors or smells. In my neck of the woods you can find it for as low as $11.99 a fifth. The taste and the smell are the cleanest you will ever experience.
I’m at the mercy of state-run liquor stores here, which limits availability. They’ve expanded their offerings considerably over the past decade or so, but there’s still a lack of the apparent variety offered in states that allow retailers to sell liquor. Wine and beer are all that’s available through retailers, and even that is limited by alcohol content.