The Pulsar NV 550 digital scope is a decent unit. It can be used day or night.
I've looked through one of these units and was impressed with it. They run about $1500,but I'd buy the battery pack to go with it.The batteries in the unit don't last long in the field,and also plan on getting an external UV light source for better night vision.
Thermal is going to cost you.They start off around $5k for the cheaper handheld units.