I agree with Caroline:
See if you have a dealer in your area and visit them. A benefit of buying from a store where you live is being able to ask questions, compare different models, make sure you're getting the right machine for your needs...and then if you need it serviced, you have someone who knows what they're doing!
.....
I have 5 machines, but I wanted to get a shiny new one for my 12-year-old daughter, so I picked up a $100 Singer at Walmart. Cheap, awful machine, thread tension extremely difficult to maintain, threads get tangled in the bobbin case much too easily. Wish I'd have gone to the closest dealer (an hour from our home) and bought a reconditioned "better" machine (Janome, Necchi, Bernina, Pfaff, Brother).