With the over abundant amount of guild coupons can GM please consider another use for guild coupons :-)
Maybe trade for food/iron/s iron or function them to buy armscraft chances?
Maybe peddler level can have option like:
Lvl 1 -- iron trade to gem
Lvl 2 -- coupon trade to gem/food
Lvl 3 -- coupon trade to gem/food/shadow
Lvl 4 -- coupon trade to gem/food/s iron
Lvl 5 -- coupon trade to gem/s iron/seal
Of course trade to s iron/seal uses more coupon but just idea