Can anyone talk to me about karaoke machines?

[beardedladydragon]

My just turned 4 year old dd has seen a friend's Frozen Karaoke machine and now wants one. It is £70 though and I am loathe to spend that on what has the potential to be played with once and put away. We have older dc who might like a karaoke machine if they could all have ago. I have seen one called the idance cube which looks more generic and gets good reviews but I still don't know if it's just flash in the pan.
Does anyone have any advice?
Thanks

We have one that can be used as a CD or DVD player and doesn't need connecting to a TV. I got it so the kids could practice singing Christmas carols last year. We do use it from time to time through the year, it can be a bit of fun on a wet school holidays day.

however, I can't see the one I bought on Amazon any more, I'm afraid.