Well, if your travels take you to Europe, I understand that some pharmacies in France and Spain sell Naltrexone OTC. The word is that if one won't, try another and another (in France, I understand they're independently owned and there are no chains) or as for a referral to a doctor that has prescribed it recently. Boxes of 28 are under 1 Euro per pill per the last report that I read.
Otherwise you could simply order them from ADC or the like and start out slowly, many report that half a dose on top of a meal and followed by lots of water through the evening will help to minimize the side effects.
If your travels take you to the middle east, beware. It's a scheduled med over there.
Stop by
http://optionssavelives.freeforums.net/ for some support and tips from the community there, it's a lot more lively.