When the kids were younger (like 4 and 6) we had a CT and they slept on stretchers (those oztrail bunk type ones that could be set up seperate as well) and light foam matresses that came with them. That worked for us because we only took the stretcher legs off and threw them onto the camper bed (it was a soft floor style camper).
We had to sell the camper after which we went to hiking style tents etc for a bit before getting a touring tent and then swags as well (swags means you can store most of the bedding inside them and throw them on the roof rather than all that bulk taking up most of your storage space in the car etc.....not so much an issue with a camper though!).
So now our kids being 8 and 10 have their own swags, got them decent ones (Burke and Wills brand) that they will hopefully keep well after they leave home
We have started looking at buying a camper trailer for ourselves to suit us now and beyond kids, but the kids will still be keeping their swags (weather they end up sleeping sheltered in a camper or outside). They absolutely love them.
So you could go for cheap swags if you're just after a convenient way to store all the kids bedding and roll it up etc and don't think the kids will end up using them much outside in nasty weather etc. But if you think it's something your kids will love and if you can see them using the swags (instead of their own tent etc as they get older) then go for a more decent one that will last them into their teen / adult years.
Only other consideration is their age, I'd probably be a little worried about 6yr old getting out of the swag at night and wondering off or something, but then again if they're a bit young just make them use it inside the camper as more of a bed until they're old enough to kick outside.
If storing bedding and what not isn't an issue and you don't want to go to the big expense of good swags then you could be better off looking at stretchers, self inflating mattresses etc, but this does require a bit more effort in set up etc.
