
Logitech G
G600 MMO Gaming Mouse
MMO button beast, but discontinued and double-click prone.

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Ordered and tested it a few days ago. The sniper button is placed way too far and the upper "tilt" button is basically unusable due to the weight required to click it. Using claw grip I was lifting the mouse trying to click the tilt button from the underside.
I went on this journey last year and gave up. I didn't like the aerox 5 enough to keep it. Felt cheap, the third button was almost too easy to press, but I never got around to finding out if I could get used to it because the mouse felt so bad in hand compared to all the other quality mice I own and have tried.
As someone else said, the Aerox 5 by Steelseries is probably your best bet. I'm not fully sure what you mean by commissioning a company to make a single mouse for you or what you expect out of that. Besides the custom shell and PCBs you'll also need custom software to bind that key to a keyboard button since Windows only recognizes mouse1 to mouse5. IF they'd even do that for a one-of unit, you'd probably pay thousands of doubloons for that and it'll probably be 3d-printed and won't be near the build quality of an OP1 let alone the software being bug free on the first attempt. If you want it to be an actual injection molded shell you could actually get a new car for the amount of money the tooling would cost and factory slot that it will take up.
I present to you the Turtle Beach/Kone XP Air I recently decided I needed a better mouse, specifically for Deadlock, and set out to replace my Razer Basilisk v3 (a great mouse in its own right). I wanted more buttons on the side to map items because I really try to keep my fingers on WASD at all times. I ordered a handful of mice, looking for mice with additional side buttons that were NOT mmo mice. I landed on the Steel Series Aerox 5, Glorious Model I 2, and the TB/Kone XP Air. I looked at the Corsair Nightsword, ROG Spatha and ROG Chakram X, but decided not to pull the trigger on them for various reasons. The Aerox 5 was an instant no. It has this weird whammy bar on the side that you flick up and down (like the guitar hero controller) that looked neat in theory, but it was really stiff and hard to use in practice. The Glorious Model I 2 was amazing and I almost kept it. The buttons are easy to reach with your thumb and it has multiple swappable buttons if you want different shapes. The m1 click action was very crisp and its also very light. I loved it. But then I got the XP Air. This mouse has some drawbacks. The M1 click action stinks, it's gummy with long travel distance and it feels bad. It's heavy at 100 grams. But the buttons, oh my lord the buttons. The side array is so perfect for items/skills with the quad button layout and the thumb rest button is literally the game breaker and why I bought it. **I mapped the thumb rest button to parry and I am able to parry/counterspell literally everything.** If you are looking for a better experience with using your active items, I strongly strongly recommend the XP Air. Deadlock isn't a twitch shooter, so the gummy M1 isn't as big a deal as it would be in COD or Battlefield (and I used it during both battlefield weekends and the side buttons were amazing there too). If you can't get over the gummy M1, and you think it's too heavy, then the Model I 2 is a really amazing runner up. My next plan is to mod the XP Air with a lighter battery and to remove some of the plastic guts with a Dremel. I've seen guides online where you can get it down to about 70 grams. That's all, thanks for coming to my TED talk.
I’m being partial here but the Steelseries Aerox family might be good for that price range. Aerox 3, 5, and 9 - the higher the number the more side buttons. The mice are in the 60-90g weight range, and imo they’re seem to be on the bigger end. Acceptably light, has good software (windows) for button remapping, generally good build quality. I’m using the Aerox 9 and it’s great for gaming and work - imagine having F1-F12 at the reach of your thumb!
Steelseries aerox 5 is a little close imho
I feel that. The aerox 5 had ping wheel issues but I love love love steelseries. They've never let me down. Thats like one of their largest flaws. And that specific mice if what i need for fps so I was trying out other things. I just got my v4. I want to try the pro x2 superstrike when it comes out but thats not until jan-march of next year. Not to mention its a heavier (65g) mouse. Guess we will see if thats to benefit or not.

Logitech G
G600 MMO Gaming Mouse
MMO button beast, but discontinued and double-click prone.

VXE
Dragonfly R1 Pro
Lightweight value champ, but small with some QC issues.

Hitscan
Hyperlight
Ultra-light for small hands; 8K dongle sold separately.

Logitech G
G502 HERO High Performance Gaming Mouse
Durable, many buttons, adjustable weight; prone to double-clicks.

Razer
Viper V3 Pro
Lightweight, adaptable shape, high performance; scroll wheel issues.

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Glorious - Model D Series

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Logitech G - G600 MMO Gaming Mouse

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