Creating a Search Engine

Hello All,

I just found this site a few days ago and their is a chop full of good information. I have a quick question. I am looking to create (purchase) a search engine. Are there company's out there that create and sell search engines?
What goes into creating a search engine?
Costs?
Can I control the searches - title tags vs. incoming links etc.
How do I spider the search engine?
I am looking for a targeted search engine and rather not have sites landing into the search engine that I didn't approve. Is this possible?

Thanks in advance for your help!
Rcart
Please feel free to email me at rcartwell@yahoo.com with any information you may have...

I have a little PHP search engine up and running using a modified version of Sphider. I have found it pretty good but there is one draw back. When you have indexed a large amount of sites, the engine begins to slow down. This would only be a problem if you wish to create a large index of sites.

Anyhow, you can find Sphider here: http://www.cs.ioc.ee/~ando/sphider/