Truckle beds - good idea or waste of money?

[scarymaclary]

I want to buy a proper bed for my 4yr old DD. I have seen lots of truckle beds (sleepover-type bed available to fit under the original bed). It seems like a great idea for sleepovers, but is it worth the money? By the time you buy the extra truckle bed, mattress and bedding - that's an extra £300.
Has anyone got a truckle bed and do they use it?

We have a truckle bed for our spare room which works fab as it takes up a lot less space but still allows us to accommodate 2 people. Both beds are equally comfy. Depends how often you'd be planning to have sleep overs. An inflatable mattress might be enough for your DD's friends and costs a lot less!