I have just been reading Joe Saward's thoughts on the subject. In it he says it would be easier to buy an existing team as most or all of the necessary wiil be in place. The only team likely to want to start from scratch might be a manufacturer. There is also the thorny question of a oncorde agreement that is not fully sorted yet.
http://joesaward.wordpress.com/2013/...a-new-f1-team/