Buying a bed for my ds

[cheekychops03]

DS (2 3/4) is ready for a bed (climbing in and out of his cot and asking for a big boy bed!). So, where do I go to get one? He saw a picture of a bunk bed with a tent on the bottom of it and fell in love with the idea but I don't know where to go to look at beds. My local John Lewis didn't have any single/kids beds at all. From a cost point of view, we are going to have to get a single bed as we can't afford to get a junior then 'upgrade' to a single when he grows out of that.
Any thoughts would be much appreciated.

The Ikea extending bed is really good, it starts off roughly the size of a cot and end up the size of a single bed.

Ikea has great beds. We were going to get an extending bed for dd but decided on "Hemnes". We are probably going to get the same for ds as he is almost strong enough to climb out of his cot.