For the sites that require a subscription and will not let you download the MP3 files directly, there's also VoiceIndigo.
VoiceIndigo: Podcasts Anytime, Anywhere
I was actually doing a search to find out if anyone had tried it when I came across this thread. I haven't used it myself yet. But, it's free. And, it seems like you've got plenty of time to kill.
Audiobay is a podcast client for Blackberries. Worked well on my Window phone, but I've heard bad things about it on Blackberries. That may be a BES thing though. Besides, they have a free trial version I assume which is enough time for you to download what you need before your trip.