Check out Allbrands.com. They always have deals on Janome's. I would recommend a Janome. With two girls sewing on it, it will get a lot of use. Do not purchase the Project Runway from WalMart. There was a news story on the Brother machines that showed NO METAL FRAME, IN FACT NO FRAME INSIDE THE MACHINE at all.
Check out this link
http://www.allbrands.com/categories/1585
The Janome machines are well made and will last longer, normally have more features and are easy to learn. The machine doesn't have to be Light weight.....the girls are not going to be moving it around a lot, are they? If they are bringing the machine to your house, I'm sure an adult would do the moving and lifting. The Janome 7330 Magnolia computerized machine if on sale for $399, free shipping and no tax if you live outside of LA at Allbrands. This machine was $479.