Floating floor over carpet

Hi, this is my first post here so I hope I'm in the right area :)

I am looking at putting in a floating floor (or laminate flooring - still getting used to all the terms!) and I have read on a few sites that it is OK to put it over existing carpet (so long as the carpet is fairly thin).

Has anyone had experience with this?

If it's ok to do, does it mean that there is no need for the underlay because the carpet is already there, or would the underlay need to be put over the carpet.

The room I am wanting to do is a little less than 24sqm - not sure if it makes a difference, but thought I'd mention it :)

Today I saw some products that were as cheap as $12/sqm - going by other prices I have seen on the net it seems very low. What ball park figure should I look at for something in a budget range, but will last a few years at least.

There is just the two of us, our dog and our cat. But at a later date we hope to rent this place out.

Any help would be greatly appreciated.

Cheers
Emma :)

[hi emma welcome
using the existing carpet as underlay will not be a problem as long as it is in good condition and not very thick,stay away from the super cheap flooring and stick to a known brand of around $20 to $30 per square metre as this will suit a low end budget the trick with click flooring as you want to use it is in the joints and how well they click together,i would run a thin bead of pva glue aloug the seam when you put them down to give a solid join as well