Electric fencing is cheap. Like, really cheap. Everything but the posts can be had for under a hundred dollars. Not sure what the layout of your property is, since 5 acres can be long and skinny, but posts can be very cheap as well if need be, 2x4s ripped in thirds and then cut in half, you end up with posts that cost less than 50 cents each and can be placed 20 feet apart. you could probably do your 5 acres for under 200 dollars.