40 Cards ($0.08/card avg.) = 1 CS:GO Key = 1 TF2 Key = $2.49
If you have a better value that you can reason out with me just let me know.
Your offer is reasonable, I'm just not sure what will happen with card price when summer sale start. I can trrade 15 TF2 keys for all your ~700 cards right away though.
The last two Steam sales the price of trading cards stayed the same or went up, pretty much across the board. With people wanting to craft the sale badges, and getting extra cards to do so by crafting non-sale badges, it was inevitable that the prices would rise during the sale.
I'm pretty happy with my price point for now. The price you propose is significantly higher, closer to about 48 cards per key. If you're interested in 40 cards/key, or have another idea for what you'd like to do, let me know.
http://steam.tools/itemvalue/#/Firestar98-753
Cards are listed there, they are valued anywhere from $0.15 down to whatever the lowest value for cards can be.
CS:GO Keys
TF2 Keys
Looking to trade 40 cards for a CS:GO or TF2 key. For trade purposes I'm pulling from the lowest and highest cards on the list I linked, 20 from each end, so it's balanced. If you want to choose specific cards I can work that out, but it'll be keeping with the average value of my whole collection, which is ~$0.08/card.
I would LOVE to do a bulk trade of all my cards for your keys! Hit me up if you're interested.