Help with Karaoke system-How to build one on Home theater system ?

First off, don't even think about using your satellite speakers for karaoke. The live vocals will most likely destroy them. You will be way ahead to just purchase a pair of PA speakers that are designed to handle live vocals. See some of the more popular PA speakers at http://www.karaoke-systems.com/karaoke-speakers.ht... .

Most standard DVD players will not play karaoke CDG discs, which is the most popular format and has by far the greatest number of song titles available. Standard DVD players also do not have microphone inputs with controls or features like digital key control. You will want to invest in a multi-format karaoke player. They are not that expensive as in the case of the RJ Tech 4200 that is now on sale for $99.00 http://www.karaoke-systems.com/tracker/c.php?i=96 .

Wireless microphones are not really necessary for a home system, although, not having a mic cord in the way is always nice. The Hisonic HS-909 2 Channels VHF Wireless Microphone System http://www.karaoke-systems.com/tracker/c.php?i=145 is very popular and sells for only $99.00.

Karaoke Home Theater

Unless your DVD player already has a microphone input,you'll probably want to buy a dedicated karaoke system. This is basically a DVD player with some extra hardware to handle the microphone. They aren't very expensive, so $300 should be plenty to get a deck and a pair of mic's.

I can't think of a good websites, but if you have a Asian shopping mall near you, there's probably a video store in there. If they don't sell the equipment, they could definitely tell you where to look.