the cost of cc from trader's ticket cost like 0.15 pc for each cc if you bought the x100 packs for 1170 pc at the time of discount other that that it isn't better than the sales.
50% discounted fragile 10 rune costs 20 tickets and giving 1600 cc. it's pretty common loot. with discounted tickets each cc costs 0,14625 bc. in another saying 1600 cc cost 234 premium bc. same ratio for 11s and so on...
1600ccs cost 320bc with cc sell.
if you buy 2x 10 stacks tickets = 252bc
4x 5 stacks = 272bc. (no sense)
so... still cheaper.
there are no 8 or 9 runes with 50% discount. at least i did not see it yet.