I just made my own, I used a piece of steel polished it and then i sloted the center and i used one of these ugly pulley's i had left over,

From there, i made a spacer and washer set, Then i had to drill out a new bearing for the center because the axel for the pulley was a little bigger then expected. Then i lock tight all of it.

I think it works pretty well. I wish that it looked nicer, But the polish steel is kinda cool... I'll be looking into getting my brother to machine arm.

Oh btw, Has anyone ever made there own chain tensioner? I'd like to see it.