If you want treated posts you should be able to locate a wood treatment company in your general area that will have them. However, they typically require you purchase in bundles. I found mine by asking a professional fence builder where he got his.
I got those at Menards. They are actually just 4x4 and 5x5 fence posts that are lifetime guaranteed against rotting. I believe they were $4.95 a piece.
Looks like fun, Richard. [img]/forums/images/icons/smirk.gif[/img] Here in AZ, I know a guy who's family has hundreds of acres south of here near Mexico... he was just telling me about the family roundup last weekend. [img]/forums/images/icons/grin.gif[/img]