My beater is a women's model Free Spirit Brittany. It's in good shape, but its definitely the bike I have that is least suited to me. It cost me $10. I ride it only when necessary. ie when the other bikes are down.

Of course, my daily bike was a freebie. A Specialized Hard Rock. Then I added fenders, a rack, street tires and lights. I get compliments on it all the time. It has cruiser good looks with the deep gears of a mountain bike. So its cheap, but not a beater.