nothing was changed with catacombs but there is changes with 1.74....
- In response to player feedback, the artifacts that previously had less than a 50% chance to drop will now drop with almost every successful completion of the encounter. In some cases the spawn rate for the encounter has been decreased to balance the higher drop rate of the artifacts. The artifacts affected include Healer's Embrace, Ceremonial Bracer, Crocodile Tear Ring, Band of Stars, Scorpion Tail Ring, Scepter of the Meritorius, Eerie Darkness Stone, Traitor's dagger and Cloudsong.
- Artifact scrolls in Volcanus have been redistributed and the drop rates increased. Siam-he up to level fifty now have a chance to drop any Volcanus scroll one. Siam-he and taurs level fifty-five and greater have a chance to drop any page of the Volcanus scrolls.
- Artifact scrolls in Aerus have been redistributed and the drop rates increased. Centaurs and cyclops now have a chance to drop any page of the Aerus scrolls.
- The final named monster for each master level encounter will now drop a random scroll from their region. Draco will drop three scrolls from Aerus.
Respawn rate on melos CB was changed with catacombs, it used to be max 30 minutes respawn, now it's 1 hour+ like the Naxos and skyros.
I've killed as many as 13 befor one CB has dropped for me after the patch.
So 15p is not really expensive at all in my opinion.