Question about Coupon price

Anyone know?!

Coupons are worhtless, so noone will buy it.

Most of the time they end up expiring or are given to trashbot, so they don't make mess in the inventory.

Maybe a few cards or a bundle game if someone is really interested, but most of the time nothing

http://steamcommunity.com/games/454510/announcements/detail/850425573967793412
"For you guys who already have Substance Painter, a 50% discount is available in your Steam inventory. "
So u can get 0 Euros for this coupon or some Dead Island Epidemic gift for exampe, or maybe few cards

1-2 cards tops. You will not get money for a coupon.

This card is only for persons whos buy Substance Painter 1 whell this is not comocn coupon

I'll buy it from you for 1 GEM, and that's still clearly overpriced.

Even though the program is expensive, and the saving is quite big, you're unlikely to get more than a token thing (like a few cards, a bundled game, a few gems) for it., due to the number of coupons for it that are out there "in the wild". As MSKOTOR said, there are 20k of them out there, and it's for an item that not a lot of people would need, so the supply is huge, the demand is not.

Most coupons cost nothing or 1 card. Because this program is expensive though, I guess you could ask even for 10 cards.

If you don't know what to do with your coupon, you can donate it. This way with some luck someone that wants the app/game can use it before it expires.

It is beyond unlikely that you'll find someone willing to buy it for anything even close to 70€.
70 cents would already be an unrealistic amount...