My first sewing machine was $400, I think. A Viking. Very nice machine, did what I needed it to do. Then I upgraded to a Bernina 430. Quite a bit more and I remember thinking that I was crazy for spending so much on a machine. And then I started using it and it made it all worth it.
I would suggest making sure your machine has some basic quilters' friends bells and whistles. I love the needle down. When I bought the Viking, they said I could just turn the wheel and I was like "oh, ok, makes sense" and then I started using the needle down on my Bernina, and it's great. Things are easier to manipulate, things don't get messed up as easily, love it
Also, my Bernina has one of those attachable trays to give you more surface. Again, didn't know what I was missing until I used it.
I also love how easy it is to wind the bobbin, but that I could live without. Some of the other things - 100 stitches, reversible stitching patterns - are cool but I could live without them.
So back to you - I would suggest thinking about the cool upgrades that you love and couldn't live without (my 2 are above) and just make sure your Janome has those