If you sit closer to the rear wall you can lessen the cancellation effect. I don't know if they still advocate it, but at one point Audio Physics used to recommend a speaker setup along the long wall with the speakers very far apart, sharp toe-in and the listener within inches of the wall.
Rather than focus on a specific price point I suggest you focus on finding a full range speaker that is fairly efficient and designed to work close to the rear wall.
Rather than focus on a specific price point I suggest you focus on finding a full range speaker that is fairly efficient and designed to work close to the rear wall.