I also have keycaps avalible here,
G815/915/ 915 TKL - Replacement Keycaps for Logitech G815/ G913/ G915/ G915 TKL Keyboards Only | eBay

White Switches are avalible here https://www.ebay.co.uk/itm/115588492058


PLEASE DON'T BUY ANY MORE SWITCHES THAN YOU NEED AS I DON'T HAVE AN UNLIMITED SUPPLY OF THESE. If you want a couple of spares that's fine, just please don't order 5 if you only need 1 for example. 

Other Logitech switces can be purchased here
https://www.ebay.co.uk/itm/114367519242