Do you have a recommendation for buttons? I know it is somewhat subjective, but I'm curious where the best places are to purchase? I was looking at the L PSL-L/CV Translucent with Black Convex Plunger and cherry microswitch but they are out of stock at Paradise Arcade shop and don't appear to exist anywhere else on the internet.
Not really. Any cheap button sold by Happ, Groovygamegear, Ultimarc, Paradise, etc will be ok. It's more about the switches than anything.
The cheap ones I mentioned that are bad feel like they were made for some other purpose than arcade. They travel down a bit, then feel like you're pushing a harder click on/click off switch (although they are momentary switches). The cherry or e-switches have a consistent resistance all the way to bottomed out and there isn't much feel from the switch itself except the audible click.
If you want the Asian style convex buttons, check out
https://www.focusattack.com/ .
I've had several good dealings with them.
I used convex buttons in a curved layout on my current cab because I wanted it to have a modern look and feel.
I really like it on games that use 3 buttons or less. On the fighting games that use 6 buttons, my fingers lose track of where they are and I find myself looking down more often to find the buttons.
I never had that problem with concave buttons in a straight-6 street fighter layout. If I ever build another cab with 6 or more buttons, I will go back to concave.
EDIT: member SegaOutrun has an outdoor cab. IIRC it's under a porch, but outside by a pool in Southern California. I don't recall him ever mentioning any issues with it.