At your lvl the arcane box isnt as useful as it is for the people that are 50+ when you need a few days of just limited runs to lvl up. It takes longer for your gear to change so its more worth the effort of making a purple.
As for the alpaca coin costumes, at first i was kinda dissapointed as well. But if you look at the long term it would break the economy cause it would be easy (in an hour i can get 100+ gold alpaca coins doing lvl 73 quests) to make green and blue costumes with leftover lost city costumes.
ok how this for destroying the economy:
least expensive item in the mall: men/ladies kimono = 499ap (rounding up to 500 for easier math >.<) x 5 = 2.5k
the alpacaite scroll (75%) (i'm guessing the price since it isn't released yet) = 1.5k
final cost for (random) green body costume = 4kap
using a 3:1 ap>gold ratio that means it cost 12K gold to make that costume, yet looking in the AH the most expensive BLUE
costume on Diamaond = 8k gold! yes that's a tad cheap for a blue (it's the kitty costume), yet the cost in gold to make a Green
costume is 1/3 more than what a blue costume is selling for in AH. even if i use a 2:1 ap>gold ratio, greens cost about the same as that blue!
lol there's broken for ya!
yes, i could buy a white item in AH for much less
(250g is the cheapest), leaving the cost of the 75% scroll as the big ticket item. still the cost in gold to go that route = 4.25k gold (2:1) or 5.75k gold (3:1) which is still pretty spendy going by auction house standards.
edit: it should also be noted that that cheap item in AH is a popsicle, so the (random) green item you end up with in the above scenario is head gear.