I agree with the other post. Monogramming machines are very expensive. You could search for shops who may be going out of business. You could call shops and ask if they are planning to upgrade their equipment soon. Call every shop within a 150 mile radius. Driving 150 miles isn't too bad if you get a great deal on a monogramming machine.
Other thing you could consider is getting a part-time temporary job at a shop. You could exchange your services for the experience (be an intern). I highly suggest this before you jump in and purchase the equipment.
Monogramming is very popular right now. Look at the catalogs, pottery barn and Lillian Vernon, to get some ideas. The only drawback is that it will go out of style wihtin a couple of years. You will then have a very expensive machine you can't sell.