Three Heroes

Three Heroes was first published in trade paperback on 1st Jun 2004 by NAL [9780451212009].
It became available as an e-book, 30th Jun 2006.

More info is available here:

The Three Heroes compendium contains: The Dragon's Bride, The Devil's Heiress and the novella The Demon's Mistress, which are about "3 guys called George".

Additional info is available here.

Where to buy Three Heroes omnibus edition e-book:
    Amazon US     Amazon Canada     Amazon UK     Amazon Australia     Penguin US

There is no audio omnibus edition. You will need to get the three stories separately.

Note: Three Heroes is still available "new" in print from PenguinRandomHouse US above.
"Pre-owned" copies of the print editon are available from: Alibris, AbeBooks, Amazon, etc.