Fiona, we did that recently when we reorganised E's room from a spare / junk room with a cot in it to a fair dinkum kid's room, but only rent a very small storage space because being in the tropics, many things cannot be safely stored due to mould/pest issues. So our excess books are at a friend's house (he has floor to ceiling bookcases), and all of our extra linen and clothes are in space bags.

But all this may be a thing of the past because we have just put in an offer on a house (WOOO HOOO). Although it's tiny, so we won't have much more storage space than what we do now in our flat, so we'll be doing yet another cull when we move. Sorry to go OT and crash your thread...

To give you an idea on price, we are paying $66p.m. for a 1.5x1.5 x 3 mtr cube - storage in Cairns is expensive!! If you don't need to make regular access to your storage facility you could consider something out in the sticks, it's usually cheaper than inner suburban storage.