Outdoor motion detectors are so incredibly expensive. Looked at the Honeywell 5300 OD (I have 1 and don’t remember it being so high priced). Also looked that the Power G one.
Any alternatives?
Any hacks to make in internal one exterior worthy?
There is an Outdoor PowerG Curtain Motion which is a bit lower priced. It is the PG9902. We do not offer it but you can buy it from a different distributor and use it with your system.
The outdoor elements would quickly damage an indoor motion as well as it is more likely to get false alarms
At that price, depending on the use case, a camera may be more effective. Do you need to trip the alarm when outdoor motion happens or just trigger an automation or alert?
[trying to think outside the box…]
Already have a camera there and adding a camera presents more complexities like power source
Ok. But curious what are you doing with the motion sense itself? Are you needing to trip a burg zone or do you just want to automate a light, warning siren, or just get a notification ?
I ask because if it is lower security item - such as triggering a notification, automating a light or zwave device etc , there are ways to get a zwave motion to work in that case. But the Surety guys may want to close their eyes when we get to the details. (lol) since officially zwave sensors are not supported. I’d never recommend that for high security but if more convenience there is likely a way. This is what I meant by outside the box. 
I need it to truigger 2 lights. An exterior light and and in interior light. Its a back door and want lights to come on in case someone is there.
Got it. So the details here depend on the panel you have and the type of smart light control the exterior and interior are (Z-wave brand, security level, etc; or if PowerG). For sake of what I have in front of me, I’ll talk assuming IQ 4.
[Note: This method has a small bug - in that the motion isn’t supported so it leaves a warning on your IQ panel that is benign. So this may not be workable depending on your preferences/tolerances. To squelch the warning the system health check can be disabled under dealer/installer settings.]
If you have z-wave switches that support the right direct association classes and you join everything at the same security level via mesh; you could:
Use a Zooz ZSE70 Outdoor motion. (Runs on battery or 12-24v ac/dc power, or both)
Directly associate it to your two light switches.
Set Parameter 2 to the number of seconds you want the light to stay on when motion is detected. (Note, if an IQ panel, set the number of seconds in Hex not Decimal)
If your z-wave switches don’t work under direct association for whatever reason, OR if the switches are PowerG, you could (but this is admittedly rather complicated):
Use a Zooz ZSE70 Outdoor motion. (Runs on battery or 12-24v ac/dc power, or both)
Directly associate it to something like a Zooz ZEN58 (low voltage relay - it can run on 12v if you have a takeover module, iq pro, etc) be sure to join at the same security level as the ZSE70
Wire the output of the ZEN58 to a zone on your takeover, IQ Pro panel, or the external inputs on something like a PG9945 or QS1137-840.
Configure this zone in group 25 and in ADC map that sensor to an automation rule to turn on your lights when this zone is triggered for the desired amount of time.
Again… outside the box. Maybe too far 