Over the last three years I've actually found three copies of this for under $100. The first copy I snagged for $20 off of Half.com - it was disc only. I wound up selling it to a friend at cost because it was the last game he needed to complete his Suikoden collection. The next copy I scored off of Craigslist in a huge lot (~30 games and a PS2) for $250 - he came up with the price by charging about 40% of what the price was on Amazon at the time. I think that made Suikoden II about $50. The next copy I got was a month ago - I'm friends with the owner of one of the local Play N Trade stores and he actually calls me when rare stuff comes in. Somehow, he got Suikoden II traded in with a pile of really awful games (Bob the Builder, Blue's Clues, etc.) - he had it marked at $80 but said I could have it for $54.99 (plus my 10% discount, so I actually got it for a little under $50). This particular copy was absolutely mint - I assume that had something to do with the fact that it really didn't fit in with the other games the previous owner had. Pretty sure it was an accidental buy on their part.
Anyways, I sold my first two copies without ever bothering to play them. Two weeks ago, I decided to give the game a go - I don't regret it one bit. I decided to keep the final copy of the game and I'm playing through it right now. It really is a phenomenal game. The story is really good - I haven't been this engaged by an RPG since I played Chrono Trigger.
The only game I ever had to actually buckle down and pay market price for was Panzer Dragoon Saga. I think I got that for $160 back when Bing was offering 40% cashback on eBay purchases (Summer of 2008, I think). That was a really great game, as well. Terribly short, though.