The pieces you have listed are great if you are going to use the equipment in your basement to practice on.
I have to agree with Steve, the best place to get started is to buy out someone trying to get out of the business.
Another way is to contact a large Karaoke dealer and see what they have for packages like Karaoke Warehouse at
www.karaokewh.com or use google and just search for Karaoke equipment.
But you say you want to start Karaoke at your business, if your business is a pub, bar, or club, you might want to look into contracting a KJ to supply everything and do the shows for you, thats what some of us do for money. What city are you in, some of us are looking for more gigs.
Jim