I don't think it's a bad idea provided you have enough cash on hand and a good system of only accepting registrations that you want. For $0.30 a registration, someone could easily bot it with fake accounts from all over the world (different IPs, would login multiple times - whatever). It sounds like you want only people with .edu email addresses? Facebook did this initially IIRC.

Thanks for your answer... So I guess I should put some limits on how much one referal fees for a month and pay only accounts that stay active more than a month...

I hadn't thought about limiting to student email addresses... but that should limit the possibility of fraud. I'm also limiting customers to only one country too (malaysia)...

This is a horrible idea, because it invites abuse. If someone sends spam advertising your site, you'll have to deal with the fallout. You might think that a few simple checks will prevent fake members, but a botnet can create fake members and make them log in as many times as the botnet's controller wants. Can you really afford to police a referral system?

a couple of questions:

target market: do you want university students' friends as your earliest members?

incentives: do you want to pay for referrals or active users (e.g., the friend uploads a pictures, posts a review, etc.)?

Target market: university students, young professional

In order to create an account one needs to upload a photo at least. I would also probably only pay for accounts that are still active after a 30 days period...