Bramiozo, maybe this will help you.
If you buy stock in a startup company for a penny (or whatever you have) a share, it is essentially worthless stock. What you are investing in is the possibility that it will increase in value. Unfortunately, that is the appropriate analogy for buying .biz domains right now.
These domains are mediocre at best and even as .coms would not be worth that much (browse the sales forums if you doubt what I am saying). So to buy them as anything other than .com is a long shot gamble at best.
If you are willing to sit on this investment for a long time, it may pay off. My guess is that it probably won't though.
Best of luck