This can hold true for any other kind of business but it especially holds true for domain name business. Patience is really a virtue if you are domain name marketeer, salesman or developer. There is no easy money here, the real return of investment cannot be expected in short term because all commodity in domain name industry relies on longetivity and reliability.
What this does in end effect mean is that you cannot expect to get rich over night and everyone telling you that you can is lying to you. To get started you only need a small amount of funds is true, but to build up on this investment and get the return you will need time, a lot of time.
Let us give a healthy example. We would start a blog on something we enjoy really much for example bowling. Now first we search for the right name, something identifying our field of interest (that has bowling in its name) or something other but brand able (like know-your-bowl.com). In either case this is the beginning, choosing the right name. After we secure the right name we can start developing our blog platform. There are many CMS (Content Management System) available for blogs and it is easy to choose and setup one, you do not need to be a rocket scientist.
Once setup, the real patience is put on a test. We would need to write interesting and contextual articles up and around bowling to get visitors (via search engines) to find us, leave their comments and let us improve on our writing style and informations we provide. This can take months and even years. After we have secured a good inflow of daily visitors (say in the 1000 page views a day) we can start hunting for sponsors. Sponsors can be your usual Google Adsense, other CPA or affiliate programs or even your local bowling club. Everybody needs marketing.
The point of our example is that we can invest lot of money at first, but the largest investment is the time and this time is what has our ROI at the end. Once established such blogging platform can bring you a healthy check every month all you need to have is patience.