Well, you see, the problem is the word PAYG.
For a member of crew looking for something for their personal use, and only wanting to use PAYG SIMs, I would suggest keeping their present "home country" SIM and then just using WiFi to get onto Vonage or Skype where they can then receive their calls on one number wherever they are (yes, they would have to tell their contacts about their second phone number, but no more than that).
On contract, there are a few things you can do to reduce the cost of roaming (if you insist on using your mobile for voice/data rather than local facilities). The likes of Vodafone World, Vodafone Passport, Vodafone Data Traveller etc.