I used to work at Wal-Mart for 7 years, I was department manager over both hardware, then for a few years in electronics, so I know what has high markup in those areas.
First off, the highest marked up items in the department are coaxial cables and stuff in that category like cable splitters and other stuff. Secondly, phone accessories like phone line, cordless phone batteries etc... All of that stuff has like an 80-95% markup.
Items like computers, tvs, game systems, and stereos all have a pretty low markup, usually 10-20%, computers being under 10%. Video games carry a 30-35% markup.
Like others say, clothing also carries a HUGE markup
