
I believe the bare edison module is (while being much weaker overall) even more expensive than the RasPi 3 (which is after all a complete board with connectors and power supply...).
The Edison mostly has one advantage over the Pi - it's a lot smaller. Great for IoT stuff, but I don't think it would be particularly useful to control a 3D printer - at least not in it's current state.
/edit:
Confirmed, the Edison module starts at about 55$ on mouser.com (with different versions available) while the RasPi 3 is still sitting at a beautiful 35$ selling price.