The other option is to add electric wire to existing permanent fences on the farm. This works very well. The most important wire is the one closest to the ground, which should be 4-6 inches off the ground, as with single-wire fences. Another wire at the top can provide an unpleasant surprise to climbing predators. I use plastic nail-on insulators on wooden fenceposts and clip-on insulators for T-posts.
I prefer aluminum wire for most jobs, but if you want to use a string trimmer to keep weeds away from the bottom wire, heavy galvanized wire will last a lot longer under its abuse.
In my experience, it doesn't seem to matter which electric fence insulators you use, or which brand of aluminum fence wire, but I think Red Brand makes a superior grade of galvanized wire.