I saw on a couple of sites that rates were listed by the hour, with a non-refundable hold-the-date fee (to be incorporated into the final hourly tally).
I would recommend having expenses be separate (if something happens you don’t want to be out the cost of travel and lodging and food!) then maybe talk to your Uncle abut what kind of hourly would be on top of that.
Because he’s family you could charge a low hourly rate in lieu of a gift.

Do research what the professionals cost (I was easily able to Google that) and work from there.

What a lovely opportunity for you, have fun with this!

DC would likely have high prices. You could call a few DC photographers and see what they charge.

Were you planning on going to the wedding anyway? You won’t get to enjoy yourself if you are working while at the event.

I would make sure you are clear on your uncle’s expectations. Are you photographing during the ceremony? At the reception? A photo of each table and candid shots? Everyone up at the alter? While they walk down the aisle? As they walk back down the aisle? Cutting the cake? The toast? The wedding party? The bride and groom in several poses? It can be a lot of work. Are they going to photos before the ceremony? You would have to be there easily an hour before the ceremony starts, and right through close to the end of the reception. At my wedding that was almost 8 hours! My photographer left after two hours of the reception and we did not do photos before the ceremony, so it wound up being about 4 hours, maybe 5. We posed for the camera like we were cutting the cake before he left, even though we weren’t cutting it yet.

I would defnitely give the kinfolk price if you choose to do it, but that’s me. I’d figure out your flight cost and add $50—$100 an hour and give all the good photos to your uncle so he is free to print whatever he wants.

Keep peace in the family by making your services your wedding gift to him. You have one day to take pictures that they’ll be looking at for a lifetime. If your uncle is disappointed about anything you do, it won’t matter if you charge a little or a lot.

I was in the wedding business for 10 years as a mobile DJ. The most frequent feedback I heard about photographers was that the couple wished they had hired a professional rather than a friend or family member.

As with any task, an experienced person makes it look easy. But beyond the technical skills of photography, the professional has a mental checklist of the standard shots, knows when to expect the good impromptu shots, and knows how to work with people to assemble them for staged pictures with a minimum of disruption to the flow of events. An inexperienced photographer can be a real downer.

It’s a wonderful learning opportunity for you if you’re interested in wedding photography, but I suggest you approach it like an unpaid internship.

^Totally agree with @bossob

I wouldn’t charge anything. Is this something you want to do for money in the future? Use this as an opportunity to start a portfolio and thank your uncle for the opportunity. Do a fabulous job and ask for the couple’s permission to use them to market your services in the future. It’s a great vote of confidence for you that they’re prepared to trust you.

I’m a freelancer, and I occasionally work with wedding videographers for the customer interviews I record and edit. Here’s how I think you should go about coming up with your estimate.

1. Check a couple of local wedding video companies to see what they charge by the hour.
2. Whatever that rate is, cut it in half, as by your own admission you’re just starting out.
3. Calculate how many hours you’ll be shooting video, then add extra time for both before and after the wedding (including editing time, if you’re being asked to do that).
4. Multiply by the hourly rate you came up with in #2.

If you feel comfortable with that figure and you think your uncle can handle it, show him a professional-looking written estimate detail how you arrived at that figure (you can find excellent estimate and invoice templates online). Be sure to stipulate that it’s only an estimate, and that if unforeseen additional work is requested of you, you’ll calculate the extra cost and tell him what it is BEFORE you do the work. Or … you could tell him that’s your firm rate and stick with it even if you have to do additional work. There are advantages to both pricing methods.

It’s important that you be fairly compensated for your time and efforts, but money should not be your only consideration. This will be great on-the-job training for you, and if it goes well, you’ll have an excellent reference for promoting yourself. You might also make some contacts at the wedding that will lead to more work.

I’ll add I wouldn’t charge anything if you were planning to go to the wedding anyway and it is a very small affair without much formality. If it is just a small ceremony with just 20 people and a simple dinner for a reception that is completely different than 100 plus people woth a cocktail hour followed by a reception with dancing and the typical interruptions.

Which is it?

My SIL’s second weddingg was the small one and the photgrapher took photos before the ceremony and during and then he left. Nothing during the cocktail hour or dinner. With that sort of set up you will be able to enjoy the socializing at the “party.”

Don’t have too much to add beyond what @bossob already said.

But to avoid the whole “mental checklist” problem, ask your uncle—and your soon-to-be aunt!—what’s on their must-take list.

I think @bossob has given you some excellent advice.

Costs to you:
Cover the costs above and beyond what you would have spent for the wedding. For example, if you were going to attend the wedding and would have flown and gotten a hotel anyway… don’t charge for those. If you need to stay an extra night… charge for that. If you wouldn’t have attended the wedding… ask to be compensated for your travel costs.

Charging for your time:
Charge for your areas of expertise. Don’t charge for your time shooting pictures, as you have no wedding photography expertise. Charge for your time editing if you have editing expertise.

To be honest, you shouldn’t take the job if you’ve never done weddings before. Weddings are a special moment in people’s lives, and if you don’t have experience doing it you run the risk of not being able to capture it correctly.

If wedding photography is something you want to do, have him hire a professional and see if you can moonlight beside photographer. And see if he will let you join him on a couple other weddings he’s doing so you can get some practice.

I did the photography for my mom’s 2nd marriage. It was difficult to get all the right shots. To do it right, you really need 2 people at different locations. I did it by running back and forth. Pics came out OK, luckily.