Alternative to Power Cranks

The cheapest alternative is probably one-legged drills...

Saving up for these as my next toy. Heard some big numbers for improvement even from pros. For most of us the effeciency gained through better pedal technique is probably better than stepping up from $1.5k bike to $2.2k bike or even from $1k to $1.7k bike so its probably money well spent even if they don't have the bling factor!