You should be able to get almost any 2-star weapon for under 2000 crowns. In fact, if you've been doing the missions, you may already have several of them. The question is: Which of these 2-star weapons do you want? My advice is to examine the *5-star* weapons, pick the one you want, and then look back in its alchemy tree to see which 2-star weapon gets you there. More thorough advice is here.
You should be able to get almost any 2-star weapon for under 2000 crowns. In fact, if you've been doing the missions, you may already have several of them. The question is: Which of these 2-star weapons do you want? My advice is to examine the *5-star* weapons, pick the one you want, and then look back in its alchemy tree to see which 2-star weapon gets you there. More thorough advice is here.