How can I export my private key from Block.io? I want to move my BTC wallet from Block.io to Blockchain.info.

As transaction fees are $10 on block.io, I would like to do this by exporting my private key and importing it on the other side.

How can I view my private key on Block.io?
Log in, click Settings -> Private Key access -> Access private keys. You will recieve e-mail confirmation with link to private key access. 

Then you will have to transfer your funds to another wallet. This is how I've claimed my BCH. The same will be for BTC but you shouldn't change Network and should set larger fee.

First of all you should get from security settings of you block.io profile: "Redeem Script Hex", and two private keys. (actually you will have some more strings and values but only these three required to claim your BCH).

After that:

Go to http://www.motelmaya.com/BCH/BCH.html

I know this seems strange and may cause doubts and believe me I wasn't sure too. But the real deal was: getting BCH (I had 0,5 of BTC at block.io wallet) or getting nothing. 

So, then:


Click +TX
Enter the redeem HEX that you received from block.io in the first box (Address, WIF key or Redeem Script)
Click on "Advanced options" -> "Network" -> Settings and change the network to "Bitcoin Cash (mainnet)"
Click New -> Transaction or +TX once more. 
Put in the amount you want to transfer and the address you are sending to (your new BCH wallet I guess - I've used my blockchain.info wallet address), make sure that the fee is not too high (I've entered something like 0.000317
Click "Submit", you will get a long HEX string. copy it
Click "Sign", paste the copied string, paste the first private key from the  block.io to the "Private key" field, click "Submit", copy the string.
Paste the string into the second box (below the "Private key" field), paste the second private key from the block.io, click Submit, copy the output
Go to "Broadcast", paste the string and click "Submit".


That's it. You will recieve TXid which you will be able to check at https://bitcoincash.blockexplorer.com 

Actually all regards should go to ohad serfaty but I can't comment the post where he advised this method because of low reputation. 

Good luck!