I use Rapid Rooters from General Hydroponics to start seedlings, They are about $20 (including tax) for 100. It seems kind of expensive but seedlings germinate fast and grow strong.
"Rapid Rooter’s breakthrough technology produces a unique matrix of composted organic materials bonded together with plant-derived polymers. Rapid Rooter plugs are manufactured using a scientifically controlled process that yields large populations of beneficial microbes in the media. These naturally-occurring microbes colonize young roots, helping plants resist disease while maximizing nutrient uptake. Rapid Rooter plugs are fortified with micro nutrients for abundant root growth. The optimal air-to-water ratio within the plug matrix results in explosive early root growth. Use Rapid Rooter for robust early rooting that supports explosive plant growth. "
"Rapid Rooter’s breakthrough technology produces a unique matrix of composted organic materials bonded together with plant-derived polymers. Rapid Rooter plugs are manufactured using a scientifically controlled process that yields large populations of beneficial microbes in the media. These naturally-occurring microbes colonize young roots, helping plants resist disease while maximizing nutrient uptake. Rapid Rooter plugs are fortified with micro nutrients for abundant root growth. The optimal air-to-water ratio within the plug matrix results in explosive early root growth. Use Rapid Rooter for robust early rooting that supports explosive plant growth. "