Dark: I would start with either Suikoden I on the PSN store, if you have a PS3 and like PS1 era rpgs, or Suikoden V for the PS2. Suikoden V has a nice going-back-to-the-basics feel to it even though it has decent graphics and good cutscenes and voice acting. The thing that's great about V is the huge story, which will show you what's special about the series. The only problem with V is that the first couple hours are a slow start, but if you're in the mood for a great story driven game you just might enjoy the slow beginning and the huge cast of characters it introduces.
You can download Suikoden I for about 6 bucks on PSN. You should probably pick up Suikoden V now if you intend to play it, as the value seems to be going up for it recently. Generally when sequels are announced game values shoot up a lot, so we'll see what happens.
I actually started with Suikoden III, but from talking to other people, that seems like the one that's just as likely to make people hate it as love it. Personally, I loved it. And I still wouldn't say I love it any less than II or V, even though those are better games all around. III is great to replay, and it's the most different from the other games in many aspects, including the crazy combat system.
Suikoden II is extremely expensive... hopefully there will be a re-release soon, near the release of VI, maybe.
