Depends what you want to do with your website. You can set up a "blogger" blog but if you wish your blog to be income earning, ie an e-commerce blog, it must be a self-hosted blog.
If the latter is the case rough costs would be:
Domain name registration(for a .com): around US$9.00/10.00 per year
Basic hosting package: around US$4.00 per month.
If you use a a good host such as Hostgator the Wordpress blog script comes free in their hosting packges plus there are thousands of free themes,plugins etc for your blog.
depends on what you want to do. I tell most people to spend atleast a little bit of money to buy a domain name and stuff but to start with you can do it all for free, there are plenty of free host you can choose from, like tumblr, blogger,webs and many more
not that i know of...
