In order to build a website like Wikipedia you need:
1. A domain name (like something.com)
2. Web Hosting (the place where your actual website files are hosted)
3. A way to build your website (Wikipedia is built using MediaWiki wiki software, so you just need to get web hosting which offers one click install of MediaWiki from their control panel)
Most modern web hosts include all three, like all of these: http://www.webhostinglist.org
iPage is currently on 63% sale for just $2.95/month!
The full price for one year of hosting is $35.40/year. (just uncheck any additional options)
(you can choose 12, 24, or 36 month plan)
Their hosting plan includes:
- Free domain name (.com, .net, .org)
- Unlimited storage and bandwidth
- Unlimited email addresses per domain name
They include one click install of MediaWiki.
To install MediaWiki:
1. From your hosting control panel, go to Website > Simple Scripts
2. Scroll down to display Wiki in the Script List
3. Click the MediaWiki name link
4. Click Install
That's it. You can choose a theme that you like and start adding content.
Hope this helps!