You don't even have to invest just in able to make 1-2 bitcoins monthly. But what you need to do is to apply your skills and offer it to the people.

There are good programmers who are nearly earning this amount and also graphic designers are good in this amount for their skills.

Many freelancers that are employed from their boss offshore are hitting this amount. But if you don't have skill to offer, better to start with some easy task.