Funny you should ask. I was wondering the same thing. I have been looking for a reasonably priced video karaoke device for my 4 1/2 yr old daughter for Christmas. I went ahead and got the star station, despite the reviews. Walmart sells the extra song cartridges and there is a decent selection, which is why I went ahead and got the machine. I'm certainly not expecting professional quality -- just something my daughter can have fun with, and use when friends come over, etc.
However, I was just looking at black friday ad listings (bf.net, I think) and saw that Toys R Us will have something called the "Singing Machine" for $49.99. It also plugs into the TV, and I wonder if it's comparable to the fisher price one. It looks less like a baby toy, and I think takes regular CDs (or maybe just the karaoke-specific CDs, but it's not a special cartridge like the other one).