In my year 11 prom in June, I spent £160 on a dress, £50 on my hair, did my own makeup as I hate how others do my really hooded eyes haha and £25 on shoes from newlook.
My dress was from jjshouse.com and I got MANY compliments despite paying almost half of most of the other girls dresses. I chose my dress because I loved the colour and style, the price was a bonus!! I recommend looking on jjshouse as you can get dresses for £50 (this isn't a plug lmao I just really like the website)
Don't got spending £300 on a dress for one night as some of my friends done, some of their dresses got ripped and they were devastated.