If you are already full of excitement because you can write a Turing-complete script into the Ethereum blockchain, I’m going to excite you even more - it’s possible to write any garbage instead of a contract code. Example of such a transaction is https://etherscan.io/tx/0x4bb32548d3b28d8bbdbe969888dff6285a0404bb314b7a8e5d81a61a313781eb . It starts with the invalid instruction code then some random crap. The fee is minimal, as nothing was executed. So I put around 1kb into the blockchain(and few thousand nodes hard drives) forever for just 4.5 Finney ($.002 at the moment). Can’t say about bigger amount of data, as my geth client got deadly broken when I tried to submit transaction of about 60Kb.
And possibility to submit invalid data as contract code couldnt' be eliminated probably by code analysis as the EVM language has arbitrary JUMP instruction.