If you're in the market to buy new, Nitto makes a variety of flat and riser handlebars which have a 25.4 clamp. They can be had for +/- $40.00 online or your local bike shop will order them for you.
I'd also suggest checking craigslist or town's bike co-op for a used version.
If you happen to find a bar that meets your needs but you don't like the color, check this thread for safe anodization removal:
http://forums.mtbr.com/general-discu...ts-547944.html
Hope this helps.