Hi, congrats on the mavic. Great drone. Rather than leg extenders you can get a launch pad and take off from there but if your decision is solid and you want leg extenders, I know a few. Polar pro is a great brand for leg extenders. Here’s the link
PolarPro Landing Gear for DJI Mavic Pro MVC-LG B&H Photo Video
I live on the coast and will definitely use it on the beach.