I'm in a similar position - have a scheduled TOEFL test this Saturday (11.02). My situation is a bit different, because I had a 2-months preparation course for TOEFL, in which I had some preparation in the weekends.
Unfortunately, except some free iPhone Apps (vocabulary, speaking) there really are no free prep materials. Maybe just have a look and the ETS OG. Other preparation materials, which I would suggest are Cambridge and Kaplan
, both more difficult that the real TOEFL, but they are not free resources.
If your English level is decent, then just buy the OG, and practice from YouTube the speaking section, which is fairly tough, because of time constraints. The remaining Reading, Listening and Writing should not represent problem areas.
Thank you very much for reading this post till the end! Kudos?