Here is a 600miliwatt 5.8 Mhz 6km FPV system with a 7 inch Monitor for your Quad.
At 600mw its a powerfull sysystem and is made by Boscam which has a good reputation for quality. They also do a 200mw but not sure if its with the huge 7 inch Monitor. This system also has a spare attachment for connection straight to Goggles and is designed to work with a Gopro or SJ4000/5000 or XiaoMi Yi.
http://www.aliexpress.com/item/6km-FPV-Combo-System-Boscam-5-8Ghz-600mw-Video-Transmitter-and-Receiver-Suit-For-SJ4-5/32324039335.html
At 600mw its a powerfull sysystem and is made by Boscam which has a good reputation for quality. They also do a 200mw but not sure if its with the huge 7 inch Monitor. This system also has a spare attachment for connection straight to Goggles and is designed to work with a Gopro or SJ4000/5000 or XiaoMi Yi.
http://www.aliexpress.com/item/6km-FPV-Combo-System-Boscam-5-8Ghz-600mw-Video-Transmitter-and-Receiver-Suit-For-SJ4-5/32324039335.html