The good news is that there are many many ISP's who will allow you to build lots and lots of sites for the same cost as just one.
So effectively once you have paid for one, you can have Lots of extra sites for free.
Companies such as oneandone in europe offer hundreds of free subdomains with their basic web hosting packages.
Each subdomain is its own website, so if our 1000 pages we talked about in the articles called how many websites is best were about cats, then the 10 subdomains might be
http://behaviour/mycatwebsite.com
http://grooming/mycatwebsite.com
http://kittens/mycatwebsite.com
http://health/mycatwebsite.com
http://toys/mycatwebsite.com
http://catfood/mycatwebsite.com
http://names/mycatwebsite.com
http://vetinary/mycatwebsite.com
http://history/mycatwebsite.com
http://funny/mycatwebsite.com
or something like that.
Now you can take the idea one step further...
http://www.mycatwebsite.com can become a portal to the subdomain sites with, say a discussion group running on it. You then ensure all ten sites link to it. In this way, the 10 subdomains help push http://www.mycatwebsite.com even higher in the rankings!
Higher rankings means more visitors and ultimately more money in your pocket.