I was lucky, I picked up my Birthing Pods before Jace was banned in standard, so I got them for about a dollar each in trades.
I find that it's generally best to activate the Birthing Pod as soon as possible after playing it. Since casting Birthing Pod takes a lot of mana or life, you want to see an investment in your return. The more interesting discussion probably lies in when to cast Birthing Pod. Usually turn 2 with Birds of Paradise is ideal, but after that I cast it whenever I can sneak it in or when I need it. Since the deck is a toolbox deck, most games I find myself trying to find a turn to play Birthing Pod so I can get the most valuable creatures out as soon as possible.
I have tried graveyard strategies before, and I found the best option so far is recursion. Sun Titan, Reveillark and Eternal Witness provide me with that. I have tried Boneyard Wurm before and was unimpressed, since I often get a few creatures out with Birthing Pod and then just bring them back over and over with recursion. My graveyard is often surprisingly small. I think Splinterfright would be counter productive if you were to mill a card you want to tutor up with Birthing Pod.
I don't really have a favorite card in the deck. I've tried to make the deck so that it stands a chance against most other casual decks, so when I find a creature with Birthing Pod it's because that creature is the best for the situation, not because it's my favorite card. I do think Domri Rade is a lot of fun. That might be my favorite in terms of having fun.
The cards that have provided the most unexpected successes are the ones without enter the battlefield triggers or death triggers, notably Strangleroot Geist, Birds of Paradise and Thrun. The realization that there may be better options than ETB effects is part of what led me to post here.
I've played with many different people over the past couple years, and the response varies. Some groups think it's just another deck, while some newer players think it's too good. My biggest problem is that I play it too much sometimes and people get bored of it.
I'm curious, what would you do with Birthing Pod if you got your hands on a playset?