I totally feel your pain on this. I was so disappointed when I finally got my Q3 and realized the ergonomics were kinda lacking for such a pricey piece of gear. I actually bit the bullet and bought the Leica Thumb Support Q3 Aluminum Black first because I wanted to be safe and use official parts, but unfortunately, it was a huge waste of money. It just didnt sit right in my hand and like you said, the price is just ridiculous for what it is. I had issues with my hand getting tired after just an hour of walking around. Luckily I found a much better budget option that wont break the bank or your hand. I've been using the Haoge THB-Q3B Thumb Grip for Leica Q3 and it's honestly been a lifesaver. It fits perfectly and doesnt block the rear dial at all, which was a major worry of mine when looking at cheaper alternatives. I was really scared about a third-party grip wiggling around and damaging the hot shoe, but this one is super stable. It costs way under your $100 limit too... think I paid like $50 for mine. It feels very secure and has a little silicone pad to protect the camera body from scratches. You should definitely grab it before your trip so you can actually enjoy shooting in London without the cramps. Let me know if you need help finding where to order it!

Regarding what #2 said about Ive spent way too much time testing different, dont overthink it. The JJC TA-Q3 Thumb Grip for Leica Q3 is only 30 bucks:

• Solid aluminum
• Leaves dial open Best value imo.

> Regarding what OmegaOrbit said about the JJC, I'd honestly be a bit wary of going that cheap on a Q3. Saw this earlier and just wanted to weigh in. While those budget options are fine for some, you gotta be careful with the tolerances on the cheaper aluminum stuff. I've seen them wiggle just enough to scratch the hot shoe finish over time, which is a total heartbreaker on a Leica. I would suggest looking into Match Technical. Honestly, you can't go wrong with any of their gear. They use brass which is much softer on the camera body than cheap alloys, and the reliability is basically legendary in the Leica community. It might be right at the top of your $100 budget, but it's worth it for the peace of mind. Just make sure whatever you grab doesn't put weird pressure on the dial... some of those generic ones are real finger-biters.

Ive spent way too much time testing different setups for my Q3. The one I finally settled on has a shallower curve which keeps my thumb in a more natural spot. My first few attempts were total failures cuz they blocked the dial or felt too stiff. It makes a huge difference when the grip sits just right... no more cramping during long days out. Hit me up if you want the specific measurements of mine.