Receive unconfirmed transactions using Insight API
It is relatively easy to build a simple program that connects to some peers in the network and receives transactions that are being broadcast. You do not need a third party service to do so.

Pycoin includes some simple examples that connect to the network and receive inv messages, all you'd have to do then is to send getdata to the peer announcing the transaction. Disclaimer: I am the author of pycoin.