After market metal rear sight for Traditions Deer hunter?

I bought a Traditions 50 cal Deer hunter last year. It came with a plastic rear sight. I checked the traditions web site and that is all they offer. Any idea if a metal rear sight can be found from another manufacturer?

The v-peep works quite well.

http://www.rmcsports.com/catalog.htm

Look at model# ML230-7.

Thanks a bunch.