I purchased a box of lens cleaning wipes in the "reading glasses" section of my local drug store. They had a 20 pack of disposable, pre-moistened lint free wipes for $4. They work fantastically well at getting sunblock off the lens of my Zeiss binos.
(*apply sunblock, accidentally touch the lens. Try to wipe that off with a rag and just smear it all over the place. Life happens.)
