I use a double uhf bowtie on my roof with an inline amplifier at the antenna. I also have an old radio shack rotor motor on the mast since my stations cluster at about 15 degrees apart.
I paid about $100 for the antenna and amplifier.
It's only about 30" x 36" and on a small mast. (used my old satellite roof mount). This link has lots of good information:
antennaweb