Building on the earlier suggestion, you should totally look at the Vello BG-C18 Battery Grip for Canon EOS R5, R5 C, R6 and R6 Mark II! I'm usually terrified of third-party gear failing on jobs, but Vello is amazing! The build quality is fantastic and it feels super secure. No battery drain issues at all, tbh! It's basically a pro-grade tool for way less cash. Definitely grab it for your shoot!

Unfortunately, I've had issues with almost every cheap grip I've tried over the years. They usually feel way too hollow and the buttons just dont have that tactile click you need when youre moving fast at a wedding. If you really want to stay under that $200 mark without buying junk, your best bet is hitting up the used market immediately. Basically, go grab a used Canon BG-R10 Battery Grip for EOS R5 R6 R6II from a reputable seller like MPB or KEH. I checked earlier and they often have them around $180-$190. Its the same pro build but without that insane retail tax. If you absolutely need brand new today, the Meike MK-R5 Vertical Battery Grip for EOS R5 R6 R6II is passable, but honestly, the weather sealing is questionable compared to the real deal. Just go used official and save yourself the stress... weddings are stressful enough as it is.

I totally get the struggle with the Canon tax because paying $350 for what looks like a molded piece of plastic is definitely a hard pill to swallow. I've used both the official Canon BG-R10 Battery Grip and some cheaper alternatives on my mirrorless bodies. Honestly, the Neewer Vertical Battery Grip for Canon R5 R6 R6II is surprisingly decent for the price if you are just looking for the extra vertical shutter button and some relief for your wrist. The horror stories about battery drain are kind of hit or miss. Some of those third-party grips dont communicate perfectly with the cameras power management system, so they can keep a small circuit active even when the dial is off. If you go with the Meike MK-R6 Pro Battery Grip, it usually comes with a wireless remote too which is a nice bonus. But since you have a high-stakes wedding in NYC this Saturday, you gotta weigh that savings against the peace of mind. The official Canon one has weather sealing that matches the R6 II, whereas the cheaper ones usually skip the gaskets. If it rains during the outdoor ceremony, you might regret the $200 savings. If you are really trying to stick to your budget, the Meike build quality is usually solid enough for a few days of heavy shooting without the buttons feeling like mush. Just make sure to pop the batteries out when you are done for the night to avoid that drain issue. Its not ideal but it works if you want to keep the cost low... honestly, for professional work, the Canon one is the only one I truly trust for weather sealing, but the Meike gets the job done for ergonomics.