Like someone mentioned, you really gotta watch out for the super cheap ones, but I stumbled on this thread and had to chime in! I went through the exact same struggle last year when I was starting out. My hand was literally vibrating from holding the camera so long during an 8-hour shoot lol. I totally get not wanting to drop nearly two hundred bucks after buying glass... it's a huge pain when you're on a budget. I ended up getting the Meike MK-6DII Professional Battery Grip for Canon 6D Mark II for like 50 or 60 bucks and honestly? It's been fantastic! I was so scared it would feel like flimsy plastic, but the texture matches the camera body really well. The buttons have that nice tactile click you want and it didnt drain my Canon LP-E6N Lithium-Ion Battery overnight like the horror stories say. Another one my buddy loves is the Pixel Vertax E21 Battery Grip for Canon EOS 6D Mark II because the rubberized grip feels super premium for the price, maybe even better than the Meike. Seriously, save your cash for more lenses or a better flash! These third-party ones are totally fine for pro work as long as you treat them right. Just double check the mounting screw every few hours during the wedding so it stays flush. Youre gonna love having that extra battery life and the vertical shutter is a literal game changer for portraits. Have an amazing time in Seattle, the weather should be great for photos right now!

Honestly, I get the budget struggle but for a high-stakes wedding in Seattle, I am gonna play the safety first card and disagree slightly with the third-party route. If you cant swing the new price, why not check for a used Canon BG-E21 Battery Grip for EOS 6D Mark II on sites like MPB or Keh? I have seen them go for around 90 or 100 bucks lately and you wont have to worry about the electronics glitching mid-ceremony. If you absolutely must go new and cheap, the Meike MK-6DII Professional Battery Grip for 6D Mark II is okay, but just be super careful. The weather seals arent as good as the official one. If it rains in Seattle... which, lets be real, it probably will... a cheap grip is the first place moisture gets in and shorts your board. Tbh, id rather rent the official one for 20 dollars this weekend than risk my main body getting fried by a 50 dollar knockoff.

Honestly, ive used the Vello BG-C14 Battery Grip for Canon EOS 6D Mark II for a bunch of weddings. It holds up way better than the cheapo brands. It doesnt feel like trash and the buttons actually click. Couple tips:

• Check that mounting screw stays tight
• Stick to original batteries Its the best middle ground imo.

Saw this earlier but just now responding. I totally agree with MetaMinds about being cautious with the electronics... the last thing you want is a power failure during the kiss. One thing to watch for is the weather sealing since you mentioned Seattle. A lot of the cheap ones skip the gaskets entirely which is a bit of a risk in that climate. You dont want moisture getting on the contact pins. Quick question tho, what batteries are you planning to run in the grip? Are you sticking with the official ones or going third-party for those too? Sometimes mixing off-brand grips with off-brand cells leads to those weird communication errors or even a voltage drop that shuts the body down, so just be careful there. I wouldnt want your gear to lock up mid-shoot.