How much could/should I charge as a wedding photographer with little experience?

I’ve been asked to be a wedding photographer for my Uncle, and he’s willing to pay me. However, I don’t have first hand experience photographing weddings. It’s something I’ve always wanted to do, and I do have experience shooting fast pace events for the marketing department I work for. I’m pretty comfortable taking the offer, but I don’t know what’s realistic in terms of pricing. I know experienced professionals charge thousands of dollars for shooting and editing, but obviously I’m not there yet.

Should I charge only a few hundred, a thousand? I have to pay for my plane ticket and hotel fees (the wedding is in DC), but should I also charge by the hour, or a base price, on top of those costs?