Nice dresses for women in their 40's

i am trying to find a nice, more formal dress for my mom's birthday. she will be 49. all the dresses I have found are either incredibly expensive wedding type dresses or dresses for teens. does anyone know of any cheap dress websites or stores for older women?

If you have a J.C. Penny's store near you they advertise women's dresses in the 30 to 80 dollar range. See the link below:

http://www.jcpenney.com/jcp/XGN.aspx?DeptID=85545&CatID=85569&SO=0&Ne=4294957900+23+1023+29+3+1490+8+1031+18+949&PCatID=85545&N=4294927467&Nao=0&PSO=0&x5view=1&CmCatId=EXTERNAL|85569&CatSel=4294927467--womens&sa=1&SelDim=4294957900~