I usually pay for the outgoing postage in US stamps and include a comparable amount of US dollars in the envelope to cover return costs, since IRCs are no longer available. Unless you have loads of different currencies laying around, it really is the best you can do. This method seems to be working so far...

Hello!
I sent a few letters a couple months ago to Georgie Henley, Ben Barnes, Anna Popplewell, and James McAvoy (via venue, since I know he usually sends preprints). I was able to send them from the US to the UK/Canada with international postage, however, I couldn't include postage from the UK/Canada back to the US on my SAE, as its not sold where I am (nor are IRCS). [color=#FF0000][u][i][b] [uk] Has anyone received a response from any of these 4 actors WITHOUT using postage on the SAE?[/b][/i][/u][/color] Please do comment! Otherwise there's probably no hope in receiving a response from them.
Thanks for reading!