Don't waste money on one of those expensive screen-cleaning solutions from office supply stores. With household items you probably already have, and this recipe from CNET, you can create your own gadget cleaner.
All you need is to mix some isopropyl alcohol and distilled water in an old spray bottle.
CNET's Sharon Vaknin mentions this is a better solution (no pun intended) than using vinegar to clean your monitor because the alcohol-and-distilled-water mix dries faster, and it doesn't smell like vinegar.
We have noted before, however, that Apple doesn't recommend using alcohol on the screens of its gadgets, so you might not be comfortable using this solution on touchscreens. Many people do without a problem though, and cleaning wipes and sprays often contain alcohol anyway.