RE: fletching my own arrows
The Bitzenberger is by far the best jig out there. However, they are pricey.
For the person that only fletches at home the Grayling will do just fine. It is made from molded polymer and costs less than $30 for the jig and clamp. Being molded the base of the clamp may not be perfectly flat so a quick sanding on a flat piece of 120 grit will take care of that.
I have one and while it isn't a Bitz it does the job quite well. For $30 you cant beat it.
I wouldn't worry about doing three arrows at a time. With the fast drying glues a fletch is dry on about 10 seconds.I don't use any of the slower drying glues any more, like fletch tite.
Regardless of which one you choose to buy they will all do feathers or vanes.
Straight and offset uses a straight clamp and helical obviously uses a helical clamp. So of you want to be able to do both then you need both clamps.