Brother has the PR-600 this as stated is a 6 needle machine, similar table top machines are made by Barudan, Tajima, SWF, Melco, Prodigi, Happy and a few others (these are known as "Arm Machines)(these also have a small sized embroidery field). Needle counts run from 6 to 15 with some 9 and 12s.
Stepping up you get into the small sized single head full industrial and commercial grade machines (these are known as "Beam Machines" they also have the largest sewing field size). There are numerous brands as stated above. IMO the upper end machines are the best for a newbe as "If it doesn't work out you will be able to turn over your machine much easier."
Getting into the Embroidery Business is not something that would be considered a small budget item. Be prepared to spend $10,000 plus very easily on machine, software, accessories, expendables and tools needed. Then comes the garments.
Here are a few of the upper end machines and the web sites. I would also recommend that you get a machine that has a minimum of a 1 million stitch memory.
www.barudanamerica.com - Brother Embroidery Machines
www.hirschinternational.com - Tajima Embroidery Machines
www.SWFEAST.com - SWF Embroidery Machines
www.melco.com - Melco Embroidery Machines
www.pantograms.com - Toyota Embroidery Machines
www.prodigiemb.com - Prodigi Embroidery Machines
www.happyemb.com - Happy Embroidery Machines
If you are new to the business remember to BUY NEW! I say this because if you have no knowledge of the machine you get tech assistance and machine repair could very easily bust your bubble! A new machine from a major manufacturer will come with a warranty, training, support, service and most everything you will need for start up. Software will also be a major purchase and time expenditure. You should learn to digitize yourself, this way you will know what is happening with designs. There is a lot to learn, it is not the turn key business that some expound.
If your intent is to really make a go at it, then by all means go for the gusto! Just do yourself a favor and research what you will need to learn before you start spending your money. Be sure to research your intended machine and buy the best that you can afford. Get reliable and reputable software, be very aware of any Auto Digitizing Software. Many of the more inexpensive offers have extremely limited editing ability over the auto digitizing they provide and the results are very poor. It is very true that YOU GET WHAT YOU PAY FOR. If it appears to good to be true well you know how that goes.
Go with Quality and you will get Quality, and that is the bottom line! The CUSTOMER Deserves QUALITY!