Wildside Press has a number of western "Megapacks" for 99 cents. There are no tables of content (at least on the SF ones I bought) but the price is right. Even if you don't buy you may get some ideas of authors to look for, including Robert E. Howard and Edgar Rice Burroughs who both wrote westerns even though they are not known for them.
http://www.wildsidepress.com/Westerns_c_3144.html
http://www.amazon.com/s/ref=nb_sb_no...2Ck%3Amegapack