You can find relatively cheap vintage 1950s prom dresses on the internet.
The first place you should start looking on is eBay: this is a great place to be authentic vintage clothing, because there are a lot of people who have such dresses in their family heirloom and they usually sell it on a very good price.
Other places where you can get vintage prom dresses are retro shops or on the flea market. The flea market is the best place to find something very cheap, but you need a lot of patience until you can really fins something that is nice and in a good condition.
Dresses from the 50s are usually very feminine, sexy and subtle at once. This means that they emphasise the forms of your body without being revealing. This was the greatest aspect of vintage dresses: they made women look cute and sexy, but they succeeded in this without showing too much and being inappropriate.
Since most women still wore a girdle or a corset under their dresses, they looked very slender. Most of the vintage dresses from the 50s have a higher waist, and if you wear a corset under you will look beautiful and truly like a vintage lady.
Cheap vintage prom dresses are the perfect choice for many reasons. First of all it is one of a kind, which cannot be said about most of the prom dresses. If you are tired that whatever you buy you will see someone with a similar dress, try buying a vintage dress from the 50s.
Secondly these dresses look good on any girl, they will make you look like a woman. They are also comfortable, most of them are long or knee length, so you won't have to worry about not being able to move freely in them.