What's the best possible fletching exp? I'm looking for a good balance between speed and price, and a profit is most preferred.

 

Please and thank you.

Fletching ammunition has basically no limit as to how fast you can spam it. (Almost certainly a loss. Broad bolts might be an exception.)

Ignoring that sort of spamming for a moment, the highest longbows you can do. (A loss, higher for higher logs.)