You may want to consider purchasing a heavy duty sewing machine, depending on what you like to sew. If you do a lot of upholstery, you'll definitely want to make the investment. If you make purses, do leather sewing or find yourself just needing that extra power, you can't beat a heavy duty sewing machine.
I purchased an Ultra Feed from Sailrite. It's a monster of a machine and extremely capable. There are two things that set it apart from the competition; one is the incredible company that makes them and the second is the price. It's very affordable.
This video goes through my machine and explains all its capabilities. If you are considering the purchase of a heavy duty machine, I highly recommend the Sailrite.