Cantina stage 8

I've only done the first node and 3* it, since then I've spent over 600 energy between daily refreshes and crystal refreshes, I have gotten 3 purple ability mats and 0 omegas. Has anyone had any success farming omegas here? I feel like the drop rate is so incredibly low that I'm better off buying them from fleet shipments which of course s.crews me out of buying zetas, but then if you don't have omegas then zetas are useless as well. I'm really thinking my energy would be better spent farming someone else rather than omegas, but I need a ton of omegas still for my arena team.