If you want to bring a computer-controlled buddy along for the slaughter prices are:
Burner (3,500 Coins): Toast enemies behind you with Burner's bad breath attack.
Cybark (2,000 Coins): Cybark slices through enemies by spitting killer gears.
Felina (9,000 Coins): Felina and her firepower really let the fur fly by shooting up and down.
Zombert (7,000 Coins): This zombie likes bullet, not brains. Absorb any flying objects with Zombert.