Amazon takes fees from buyers ?

If you mean any extra fee appart from the actual price of the product you want to buy, of course not!
They do charge taxes though depending on the state you are, but so far in California they have never taxed any digital download.

Example:
Dark Souls: Prepare To Die Edition [Online Game Code]
PC Download:............$7.49
Total Before Tax:........$7.49
Estimated Tax:...........$0.00 <----------- This is what you need to check before you buy.
Total:............................$7.49

They dont take any kind of fees that I'm aware of. I have bought several games from Amazon and it charges me with the game price only. (and of course, a few cents as Paypal fees, blah blah, usually less than 0.5-1$)

No fees.

Amazon charges taxes for purchases from some states in the U.S. Here.

There's taxes in a few states now

Amazon has always charged tax if they had a physical presence in a given state.
That means, if they have a warehouse, they must charge tax to residents of same said state.
The more warehouses Amazon builds in new states, the more states get added to the taxed list.
plain and simple.
That is also why Steam charges you tax fees, if you live in WA state and Blizzard charges you tax if you are in CA or WA (possibly other states too) and why Newegg only charges you tax if you are in CA.

In the US there are several States with a tax on digital purchases. If you live in such a state, use a service like borderlinx to avoid taxes. Same can be used to buy from Amazon outside of the US.

If you buy Dark Souls for 7.49$ the real price for the publisher is about 5.5-6$ and Amazon take the rest.