TigerDirect’s TechBash will welcome 20,000 to Marlins Stadium on Nov. 7 from 7 to 11 p.m. for a free event that will feature more than 150 vendors, entertainment, food, exhibits, opportunities to purchase the latest technologies at Black Friday-like prices and “many surprises,” say the organizers. For the first time, the event will also include the finals of the Build Your Own PC Race For Charity…