Mine is mounted to the top, under $25
I built it from a 12" stainless fold down light and a piece of an old fiberglass antenna.
In the upright position it sits abbot 6" higher than my radar, and is the highest point on the boat
I'll try to find a better picture, in the picture below it is angled back for trailering, but I cut the 12" stainless extension that came with it just under the light and extended it with an old vhf antenna.
Replaced the standard festoon bulbs with LED festoon bulbs ordered off eBay, same color temperature and brightness as original bulbs
8 years later, still going strong
Relentless