The talks appear to be preliminary. If the two parties can't agree on an extension, Sale will make $600K in 2013, after posting a 3.05 ERA with 9.0 K/9 and 2.4 BB/9 in 192 innings in 2012.
Sale will be arbitration eligible for the first time next winter, and he has 2.061 years of service time. Trevor Cahill and Clay Buchholz's contracts, which are both around $30MM (and also include club options) and were signed when those pitchers had between two and three years of service time, provide rough blueprints. (See MLBTR's Extension Tracker for more.)
The White Sox would likely want to cover Sale's four remaining pre-free agency seasons, along with at least one free agency season. Sale, meanwhile, would be guaranteed north of $30MM, mitigating his risk in the event of health problems or ineffectiveness.