I wrote an article on how to build yourself a tournament-level deck for the 2018 Store Championships season with as few purchases as possible: https://cryoffrustration.wordpress.com/2018/01/25/netrunner-competitive-decks-on-the-cheap/ It includes links to decklists on NRDB and lists of packs needed to make them.
It's addressed to beginners who want to move into tournament play but aren't sure if they can build anything good with the packs they own, or people who left the game and sold their collections years ago and want to come back.
Decks should be viable all the way to Regionals season unless some new meta-warping card is released during Kitara, or a new MWL makes them illegal.
Let me know if you make the top cut at a tournament using one of these so I can send you an e-high five!