Actually this is all upto you. You can create a niche site in only $1 as well. This depends on you how you have control over it. How you can figure it. This is important acctually. You have to focus on your ability. If you have good figure on Search Engines Optimization, You can turn your business profitable if you have even a zero budget website. So this is really an essential thing for niche websites. Without SEO you are dear here.
This is not possible for those people who don't have knowledge about SEO. I would like to say- those people dont have good figure on SEO, they should not try any niche project.