Steam – Does buying a TF2 key unlock the community market

Yes,I bought an item for Dota 2 online rather than in-game shop and my progress towards the card increased,don't see why it would be different for TF2.

When you buy items online the system asks you to log-in with your steam account to finish purchase;in-game store is essentially just a simple game web browser to display the original online store(Why?It is easier to maintain one store than 2).So in the end whether you buy something online or in-game it goes thru the same account and the same system.

Also the system is retroactive,meaning all things you bought before trading cards will be counted as you bought them now.So the system will checks your receits and they are the same for both stores.

If you want to check for yourself you don't have to spent 9$,you can purchase the cheapest item you find and then check if you "progress towards next card" has increased.

Nope, you'll get everything you would if you bought it in the Dota 2 store.

They only differences would be that you won't contribute more money to the prize pool for the winning team and pushing us closer to Techies the ability to select the next hero Valve adds. I also suppose that the compendium will say that you've contributed $0.00 to the prize pool instead of the normal $2.50 that it says.