Arcade Forums:
https://forums.arcade-museum.com/
https://www.arcade-projects.com/
https://forum.arcadeotaku.com/
https://www.neo-geo.com/forums/index.php
Arcade PCB Shops:
Here is a list of stores and their web sites that sell Arcade Games.
Keep in mind that not all shops will mail items outside of Japan, so you
may need someone to go that store for you, buy the item, and then ship
it to you. Also note that some sites are not in English and you may need to use a online translator if you do not know the language.
Ali Express - https://www.aliexpress.com
exA-Arcadia - https://exa.ac/en/games-list/?v=0f177369a3b7
HK Legend - http://www.hklegend.com.hk/?page_no=6&lang=0
G-FRONT - http://www.gfront.com/
Game Kanaya - http://www.game-kanaya.com/index.html
Japan Dealer - https://www.emporiumretrogamingshop.com/en-us/collections/arcade-games
Mak Japan - http://www.mak-jp.com/
HK Legend - http://www.hklegend.com.hk/?page_no=6&lang=0
G-FRONT - http://www.gfront.com/
Game Kanaya - http://www.game-kanaya.com/index.html
Japan Dealer - https://www.emporiumretrogamingshop.com/en-us/collections/arcade-games
Mak Japan - http://www.mak-jp.com/
Arcade Parts:
Arcadeshock - http://www.arcadeshock.com/
Amusement Game Services - http://triplemoonstar.brinkster.net/theshed/default.asp
River Service - http://www.rs2006.co.jp/overseas.htm
Arcade Cabinets:
Coinopexpress - http://www.coinopexpress.com
Highway Entertainment - http://www.arcade-game-sales.com/
Shadaloo - https://www.shadaloo.eu/
Tessin Create Company - http://www.tsc-acnet.com
The Game Room - http://thegameroom.com/arcade-games.shtml
Arcade Auction Events & Sites:
Arcade Auction Events - https://auctiongamesales.com
Arcade Auction Events - https://bid.captainsauctionwarehouse.com
Craigslist - https://www.craigslist.org/about/sites
Ebay - https://www.ebay.com/
Yahoo Japan - https://www.yahoo.co.jp/
Rinkya Japanese auction bidding service - http://www.rinkya.com
All in one Arcade Machines:
Arcade Maverick - https://www.arcademaverick.com
Arcade 1up - https://arcade1up.com/
iiRcade - https://www.iircade.com/
Useful Apps:
Google Translate - https://translate.google.com/?hl=en&sl=ja&tl=en&text=http%3A&op=websites
Currency Exchange Rates - https://www.xe.com/