I would not use rubbing alcohol. I would imagine that can cause serious problems. Bleach would be your best bet for a low cost sanitizer. A better option would be idophor (sp). I have heard you can get it at feed stores for really cheap. Even at a home brew store it is only about $10 for a bottle that would last you most of college if you are careful. The advantage is that this is no rinse. If you are not careful you will get off favors with bleach or if your rinsing water is contaminated you will then loose the batch. One batch of beer lost to infection or off favors it $20-$50 which is alot of sanitizer.
If you want to use bleach check out www.howtobrew.com. It should have the ratios there.