What I'm looking at right now is something like:
Merchant purchased: X durability, 0% activation speed
Regular crafted: X + 50 durabiltiy, 0% activiation speed
Imbued crafted: Variable durability/%speed based on materials used (tested and Newhaven Copper is ~15% and Flatlands Tin is ~20% I think with durability increasing)
Imbued crafting doesn't always meet player expectations but those first few tiers I try to make sure has the expected curve. Like if as you skill up you go from
1-10: 500 durability 15% speed
10-20: 600 durability 20% speed
20-30: 800 durability 10% speed
30-40: 500 durability 40% speed
etc.
This is all theoretical, but eventually you get into stuff that may provide choices, especially as 1-10 and 10-20 materials reappear at high levels giving you some choice between more durability or faster execution or a mix of the two.