The IKEA bunks are very cheap and I see them everywhere in hostels. They seem to have one problem: I have seen a lot of broken upper bed guard-rails. Apparently this happens when a heavy person tries to pull himself up too fast. The result is that this person makes a hard landing on his butt. :D
We are using wooden bunks, but I have just ordered two steelpipe bunks there: http://www.sleeptite.ie/
Unfortunately no pictures on this website, but they´ll send you plenty. The beds are pricey (compared to IKEA) but obviously much more robust and a lot nicer too.
If you don´t like their design or have ideas how to improve it, they´ll co-operate with you and build for you what ever you want.