I like to played themed sims and Amish sims as well. Check out this link, it's not Amish clothing, but as prairie clothing it works well. Also check around Mod the Sims, they have some Victorian suits and things that would work well for men. Also they have a few things that could work well for your female sims. Hope this helps!
http://www.all-about-style.com/themes_prairie.html