I consider Inexpensive $500, but couldn't get my mom to spend more than $250 on her new bike, she didn't think she needed an expensive bike. Entry level triathlon bikes are $2500. People at walmart consider the $56 sale bikes inexpensive and the $189 "high end" bikes to be expensive.
Good luck on defining this, the major problem is most peoples perception of bikes is not the one shared by us on this board.