I am really big into die cutting. I agree with the other girls if you are serious about getting into the vinyl business look into an industrial machine. You can buy an industrial Silhouette type machine through the Graphtec line. There are a lot of good Graphtec dealers online. If you are wanting something a bit more heavy duty look into a Roland machine. The Cricut is technically a Roland machine but was designed for the at home artist/crafter while Roland is more designed for business use.
The main thing you will want with a business vinyl machine is a good software package. This will be bundled with your machine. You will also probably want a machine with Illustrator support if you are using the Adobe lines.
This forum is pretty good at knowing their plotters/cutters for the vinyl business:
http://www.t-shirtforums.com/vinyl-c...ers-transfers/. It will help you find a starting point.