This thread title is pretty misleading. GS is not running a "free" Edge card promo with $50 trade-in. It has always been the case that, if you trade in enough games, the extra 10% from Edge will cover the cost of the card. Not exactly a a deal.
While You are correct, this is a deal because it is exploiting the current trade in offer towards new item purchases which is a limited time thing. Generally, you would need to trade in 150 bucks worth of games to cover the cost of the edge card (not including any trade in promos) 10% of 150 = 15..which is the usual cost of the edge card.
So, yes it is not an official gamestop sale per say, but it is an exploit of the system, one in which I assumed would be self-explanatory for everyone who uses these boards and understands how to exploit offers to get the maximum benefit for themselves.
I do, however, apologize for any confusion the topic may have caused. However, the topic title is still accurate and not misleading. If you trade in 50 dollars in games, you get an edge card free.
Edge Card = 14.99
trade-in towards new promo = 20%
instant edge bump up = 10%
10% of 50 = 5 dollars