Keep a look out for lovely second-hand outfit, last few weddings I've been to have worn second hand, doubt that the dresses had been worn more than once or maybe twice. Nobody knew and even if they had found out nobody would have cared. How is it different from hiring an outfit. Sometimes people sell an entire outfit with accessories, I'm on a facebook page for scarlet and jo dresses, and sometimes this happens, someone has a hat/fascinator and jacket or bag to match, shoes even but not so easy. As the person no doubt lives a distance away from the venue no one will have seen it
So why not consider second hand, if nothing else seeing what others have worn and the brands might give you ideas of what you want. You can always keep looking for something new and decide to buy new.
If you do buy secondhand, you could treat yourself to new underwear, maybe a make over with some make up perhaps a bit dearer than you might usually use, some new perfume, with the money you saved