I have found there isn't a lot of differences in prices in the name brands if buying from a dealer. The manufacturers have sales that they all have at the same time the only exception is if they are vending at a local quilt show. Even then if your dealer isn't showing there they will normally match the price (unless you were buying a demo). I think (I have been wrong before) that the dealers are told what they can and can't do and with very few exceptions stick by that.
the big difference between a car and a sewing machine is the car dealer wants you to finance (they make extra $) whereas the machine dealer will a lot of the time give you a 5% discount if you pay cash (they have to pay for that special financing or credit charge)