DV Info Net - DVD Distibutors/ types of contracts to expect

Okay, so I am in the editing stages of a four-wheel drive enthusiast DVD that I am hoping to get distributed nationally. What should I look out for when talking to distributors? What distributors have you all used? I have talked to VAS Entertainment and they seem very helpful, but I am still "shopping around". Nothing is final until I get my DVD's sent out for companies to approve and start negotiations, but I figure it's never to early to start learning what to watch out for. I wasn't sure if most just do royalties, or if it would be a flat-rate or what... There are similar videos to mine sold nationwide at best buy, sam goody and other similar stores so I am confident that it has the potential market. Thanks in advance.