It really is very good, isn't it? Unfortunately, I can't think of a close alternative...it is absolutely unique. There are alternative good leather scents, but none has the same tart, crispy feeling that Cuiron has.
My other favorite "pure" leather is Tom Ford's Tuscan Leather, but while it's very good, I consider it the smooth, velvety counterpoint to Cuiron, rather than a close peer.
If you are able, the thing to do might just be the drop the cash on a bottle from Ebay. It'll cost about has much as Tuscan Leather anyway.