IMO if you want GAP then buy it from a regular insurance company. Don't buy it from the dealership as they will charge you a huge amount. Shop GAP prices before you ever get to a dealer.

Don't let them brow beat you into a GAP policy there - right in the contract it states that it is optional yet the finance guy usually tries to add it to you contract price. If you are putting down money so that the amount you finance is less than the value, then don't get GAP insurance.