If you have lots of antique stores you might be able to find a gem that meets both your budget and your taste. Otherwise you could make your own mirror.
Assuming you found an antique frame you loved, you could probably go to the hardware store to find glass, and then have the glass silvered by a pro. Glass is heavy, though, so you'd really have to be sure the frame could stand up to it.

Here's a site that describes how to make your own mirror, from the frame onward: http://www.uniqueprojects.com/projects/wallmirror/wallmirror.htm. If making your own frame isn't in your plan, you might be interested in the other info such as mirror backing, glass thickness, etc. 

 Good luck!