I'm thinking about something more like this:
Let's assume that each curio has a "time" to be mastered. For every curio that YOU have mastered, all your CRAFTED curios would have a small bonus.
Bonus suggestion: 0,5% Total LP or decrease the time to finish the study by : 1/ 1 + ( N * 0,05 ).
N = Number of curios mastered.
Why I think this is a good approach?
1º There will be always better curios and it will be hard to balance. So it can give a bonus to the "best" curios in the game if you study others curios too, including the bad ones.
2º People would trade more curios, since they would be just looking for new curios to master, heating the market

3º I guess that only YOUR crafted curio should receive the bonus, because it will be less incentive for alting. If your main character is the one who study a lot, he should craft the best curios( at least). So the bonus is not for every curio from everywhere or anyone. It will be only for curios that HE crafted.
4º Just one more note: If I mastered 50 curios, my crafted curio will receive the bonus and, if I give it to someone or trade, the others will receive the bonus too. So people can even be "specialist" on selling bad curios with a good bonus, wich may be worth more than crafting yourself.
Tl;Dr;
For each curio mastered, your crafted curios receive a small bonus: Inscreased LP value or Decreased study time.
Time frame suggestion: 15 - 20 non stop study ( 360 - 480 hours )
Extra: Foraging Curios could double bonus
