I was just looking at new bow navigation lights today, at Wrst Marine and at Bass Pro.
If you have 2 separate green/ red fixtures, you can buy an LED replacement set for $65 at BPS... (vertical mount type... They didn't have the deck-mounted type like I needed, but I found them online for about the same price at Jamestown Distributors). But If you have both colors in a single housing, it was even less. I am thinking about getting new ones myself, as my lights are terribly unreliable.