Yes, it is pretty expensive compared to, like, chickenwire or a couple bare electric wires. It is cheap relative to more useful things, though
The main sources I know of are
www.premier1supplies.com and
www.kencove.com - in the U.S., you are unlikely to beat those prices in an acceptable quality product. Premier's is roughly $175 for a 160-ft roll (you can also buy half-length rolls for about half-price); I am not sure of kencove's prices (I've only bought it from premier).
Organic and hobby farms afford it by deciding it is worth the money -- neither of those are usually low-startup-cost things anyhow
What it's more affordable than is PERMANENT predatorproof fencing in a bajillion little rotational paddocks. It is not cheaper than a small run attached to the coop, or free-ranging, though
Most backyard flock owners are not going to need more than a roll or two of it, though, max. Which is not that bad - two rolls would be a smidge over $300 plus maybe $80-200 for the charger (unless you can simply attach it to an existing livestock fence charger, which is what a whole lot of people do, thus not having to buy a separate unit).
You do want to make sure you undestand its idiosyncrasies before committing to it -- the ground under the fence needs to be kept shaved to the ground (ie. move the fence whenever the grass grows up a bit, and mow, and reset the fence -- easy, but you HAVE to keep up with it) and it is vulnerable to wind and ice unless tied back very stoutly with extra posts, and it is not a useful fence in snowy times of the year.
But for rotational grazing of a well maintained pasture it really is great and a big money-saver.
Good luck, have fun,
Pat
