Each episode of The Flash is made with 1.5 - 2 million dollars per episode. The Flash is made with a smaller budget then usual TV Shows are made with. Most TV Shows are made with 4 - 14 million dollars per episode. Grant Gustin, Barry Allen, has a network of 1.4 million dollars.
Tom Cavanagh, Harrison Wells, makes about 100k dollars per episode. Jesse L. Martin, Joe West, also gets paid about 100k dollars per episode. Grant Gustin gets paid about 30k per episode. The reason for this is because even though Jesse and Tom don't play the main character, they are very talented actors, where as Grant, who is also very talented, is a newcomer and hasn't been through as much experience.