How much is a 1967 one sided dime worth?

Actually, it can't exist with only one side, so I assume the reverse is blank. You need to determine why it is one-sided. If it weighs significantly less than a normal dime or shows polishing marks, someone has removed the back of a normal dime and it is not worth anything. But it could be a full-brockage error, meaning something (usually another dime) was between the planched and die when it was struck. These will bring a significant amount, but nothing to plan an early retirement on. You might search eBay to see if any similar errors have been sold recently.