First, know the features you really want, wider throat, blanket stitch, etc. and
Second, sit down and sew on the different machines. Top of the line may not be what's best for you, the models with lesser bells and whistles may have the features you want and at a much lower price.
When I was looking for a new machine I was sure I was going to buy a Bernina but I didn't feel comfortable using it. Went to a sewing machine/vacuum shop that was a big messy place but since it took me so long to drive there I'd try out the Pfaff I came to check out. Well I bought it because I felt so comfortable using it and still do.