The term generous is a bit subjective. It is much better to make either a firm offer, e.g., "10 gold", or an offer with some wriggle room, e.g., "5 gold but I am willing to negotiate".
A Woodworker requires 3 planks of treated ilex, 3 planks of treated mallorn, a mithril flake, and an Elegant Cowbell Recipe (a single-use BOA recipe costing 20 silver branches). Naturally, most Woodworkers will be able to provide the wood. The silver branches, which are acquired by questing in Lothlórien, are BOA. Most serious crafters will have a supply of mithril flakes, but if not they are currently selling for 400 silver on the AH.
A Woodworker with the best tools has 25% chance of critical success, i.e., the Exquisite Elegant Cowbell you desire.
Optional ingredients include either a Scroll of Supreme Woodworking Lore (2 Rune-carved Tablets + Etching of Moria) or a Scroll of Woodman's Lore (1 Tome of Wisdom) from a Scholar to add 12.5% to the critical chance, and an Elven-wood Oil (cost 5 silver branches) to add 35% to the critical chance. Add them together for a maximum critical chance of 72.5% (25 + 12.5 + 35).
Post your offer and I will consider making the cowbell for you. I have or can obtain all of the necessary ingredients.