I am a graduate student making $26k/year. I manage to put away $5k/year into a Roth IRA, and the rest mostly goes to bills and living expenses. I still owe a little less than $80k on my 2bdrm condo, with an interest rate of 3.5%. My question is: I usually have ~$200/month left after everything else- is it better to put it towards the principle on my condo (which is what I have been doing) or put it into more mutual funds? I already put the max into my Roth IRA, but I could start a regular mutual fund account.