CS:GO Case Keys (question)

Well, welcome to Steamgifts. I'd like to suggest first that you thoroughly read the FAQ. You didn't break a rule, but all new users definitely should (^w^).

This thread doesn't belong in Deals, but General or Off Topic.

I also think googling this would work very well.

Purchasing the keys from their in-game stores will always cost you $2.5, so that's the price you always go back to. However, sellers might increase/decrease that price due to cyclation of the keys though the market. Thus, a reasonable price(considering buying using Paypal) is $2.2

you can get it easy for 2$

Rocky's comment above is not entirely correct

TF2 keys cost approximately $2.45-$2.55 from the store but can be acquired for approximately $2 elsewhere
CS:GO keys cost approximately $2.80-$2.90 from the store. No idea how much they cost elsewhere, but probably about $2.25-$2.50

You should not accept prices higher than $2 if you're paying with real money, it's reasonably easy to find traders selling both single keys and in bulk at those prices (though usually buying at least 5-10 at a time is the norm).