Contact Cleaner VS Alcohol
The 100% alcohol would be considered as the ideal material to clean any electronic contacts as they evaporate quickly and leave no residue behind.

But the only problem with them is "100% pure alcohol is too expensive". (Its also one of the most explosive components.) So normally the manufacturer mix alcohol with other components (which might or might not be volatile) so that the cost and dangers can be minimized. Still alcohol is the main content of contact cleaners.

However the best solution for you would be to be reasonable with both cost and the materials used in the product that you want to buy. You can always check about the ingredient components that are used to make a cleaner. Depending on your design requirement you can purchase a specific one.

Nobody would advice you to go for 100% pure alcohol only unless you want to clean some really expensive equipment that has gold platting over the contacts.