A famous online store that sell everything about mechanical keyboard. They are from China and ship all over the world. Most of their products are manufactured by themselves.
Essentially a group buy site. They mostly sell very high end products. Keycaps here are great! They allow many people to pool their buying power in order to buy large shipments directly from a supplier, so you can get the stuff you want at a discounted price. However, they offer very few items at a time, time frame for each item is limited and the pool filled up really fast. Once an item is sold out, you have to wait for a long time until they have more stock.
https://reddit/r/MechanicalKeyboards
A great subreddit for every mechanical keyboard lover. You can post your questions about mech kb and people will help you out. People also share pictures of their own keyboards, tips and tricks, which keyboards is on sale, etc. Good posts everyday!
An online marketplace like AliExpress. I have bought from both AliExpress and Banggood. Banggood has more items for mechanical keyboard community. They are also faster in terms of shipping, and better in terms of customer service
https://www.reddit.com/r/MechanicalKeyboards/wiki/switch_suppliers
This is my go to site when it comes to buying parts for my mechanical keyboards. I always come here first to research about parts that I want to buy. There are so many useful tips on selecting parts. People who posts here are very knowledgeable and friendly as well
https://www.coolcable.co.uk/gb/
A good looking keyboard needs a good looking cable. This site has everything you need about cables. My favorite part is that you can actually customize your order, from cable length, color, to connectors. They are pricey, but I think it’s well worth the money. Expect at least 2 weeks for shipping.
A Guide to Mechanical Keyboards 