I picked this up waaaaay back in the day. During development they had a deal going, the earlier you bought the game the less it cost, price would go up with each update. I paid $2 for it when the first alpha build was released, simply because it sounded like they had a brilliant idea. And they did
Probably the best $2 I've ever spent as well. Great game, and if you don't pick it up while it's on sale you're crazy. There's an expansion in the works, Mount & Blade: Warband, which adds a single player campaign, improved graphics, improved AI and the main thing everyone's been asking for: Multiplayer.
Riding round on horseback hacking people to pieces, taking hostages, raiding/defending castles, and soon we'll be able to do all that with other toggers, be nuts to pass on this opportunity if you ask me.