Seriously though, gowns aren't essential and I would say if you want to get one, go second hand. There is usually a sale of second hand ones in freshers week although get there quick as they sell quickly. I've used mine a bit because I did the whole ambassadoring thing (taking prospective students around the town). Apart from that, formal hall dinners, pier walk and other such traditional things. And if you get an academic mother who makes a raisin string for you, your gown is where you are supposed to hang it.