I use a company in Scotland who still make them, they don't supply direct but if you contact them you may find they have a retailer near you go to http://www.glasgowsteelnail.com to view the nails
I'm amazed to see that range at Rutlands. I had no idea that there was anyone making copies of forged nails, they do look a bit rough around the edges though ... and I know the square cut end is good for punching through to avoid splitting but it's not much good for clenching.
Here's a couple I made the "real" way ... headed through a block with a domed top to make a concave on the underside of the head to get a nice, tight waterproof connection with the wood. Good for exterior stuff: doors, benches, carts etc.
I say "real" but these are mild steel. I've tried in vain to make them from wrought iron - I can't get the points thin enough before they start to separate into strands.
As for the price ... the Rutlands jobs seem pretty cheap to me - when I think about how long it takes me to make enough for even a small project it makes selling them impossible. Such was the Birmingham/Black Country nail industry, barely viable; even with all the kids involved.
They are made for nailer guns and come in strip form. Most often used for nailing sarking on roofs, I used to pick up unused boxes of them on site. If you happen to know anyone on a site, particularly timber frame housing, you might be able to get them...bosshogg