Check out sites like pricepoint and steepandcheap, they might have some deals.

I have 510s for when I run platforms on my mountain bike and they're super stiff, but still easier to walk in then spd/mtb type shoes. I'm not sure what I paid for them, but I think it was around $50 on pricepoint at the time.

Actually, it looks like pricepoint has a fairly nice selection right now...
Mountain Shoes | Shoes | Discounted Mountain Bikes, Road Bikes and Cycling Gear at PricePoint.com

No idea how these Giro's are, but $30 doesn't seem too bad to give them a shot:
Giro Jacket Mountain Shoe | Giro