We wanted to install fencing that was a deterrent to fur bearing beasties and also cost effective. Because our plot is at a community garden and not on our own property, we didn't want to put in fencing that cost so much that it out weighed what we were saving by growing our own produce. So, we decided to used 60" Metal T-Bend posts and 40" tall, 1" plastic mesh garden fencing secured with UV protected zip-ties. In total we spent $100 for the materials - that's not including the gate that has not yet been built.
The fencing is high enough that a deer can't walk over it and the holes are small enough that a bunny can't fit through. To prevent Mr. Bun Bun from wriggling under we folded about 3" of the fence up at the bottom and then secured it at intervals with sod staples. I don't think it's impossible to prevent a motivated creature from invading our garden, but it's something.
Oh yes, I know it looks like hubby did all of the work . . . and I'm not saying he didn't do more than his fair share . . . but I did help by humping materials, acting as his assistant and whatnot. Just sayin'.