White sugar will give you the cheap carbon source you are looking for, so go ahead and use it. Dissolve your sugar in hot water, allow to cool, store for later use.

Molasses has other stuff in it that is good for the beneficial soil bacteria. Plus the othe nutrients that have been mentioned already. That's why everyone is so keen on the stuff. If you want to get real fancy and get the most possible bang for your sugar budget, molasses + Sweet + MycoStim. Awwww, yeeeeeeah, G!