If you're looking for a reasonably priced, high performance butterfly knife, you'll want to consider a McAhron Custom Balisong.
The McAhron "True Grit Dagger" butterfly knife has a double-edged sharpened blade that is only for the truly brave flipper! The blade is over six inches long and has a hand satin finish. The handles are bolstered titanium with red G-10 scales. The pivots have silicon bronze washers and stainless bushings that perform well and keep handle play to a minimum. The True Grit Dagger is a latchless balisong.