The locks are massive and expensive in comparison to what you'll see on the rack at a department store, but they're bombproof and when used in combination, a thief will walk on by.
Here's some prices. Those are actually decent prices. The important issue here is to look at the guarantee provided with the locks. $3500.00 guaranteed replacement with the chain and $4500.00 when using the U-lock, if your bike is stolen while using the lock. I use both.
Keep in mind that it isn't a good idea to buy your parts through Amazon, just go to JensonUSA or wherever. I only used Amazon as a reference.