Originally posted by lotech IC... I did not use flash often ever since I switched to digital, so have zero idea about the current technology in flash design !
You have two choices:
1) Pentax P-TTL with a Pentax master flash and P-TTL slave flashes from Pentax, Metx or Sigma
2) Manually adjusted flashes using radio triggers from a number of makers. Dozens of options, almost all far cheaper than the Pentax gear.
For manual you have three choices:
1) Ebay triggers and cheap new flashes or older good quality ones like the Nikon SB-26
2) Cactus ecosystem with Cactus v6 triggers and Cactus RF60 flashes
3) Yongnuo ecosystem with their triggers and flashes
Both Cactus and Yongnuo allow some control of the remote flashes from the camera just not automation like P-TTL.