I think changing to the line system would cost more than that, but not much more. Usually you have some line laying around although some spyderline or excel racing would work very well and is about maybe 6$ for enough. a couple small ronstan 666 blocks (7$) and some cleats. The breakaway cleats are a little pricey though- 25$ each. I guess some bungee too to hold the rudders up also.
The system is not necessarily maintenance free of course. If the glass rods work well for you then by all means keep them... but having fiberglass fly around if it does break isn't my idea of fun either.
What is nice about the system is that you can uncleat the rudder hold down line and then hold it or cleat it with the boards partially up when heading into the beach.
At the risk of complicating things further, on the blade, the line comes out of the rudder about the same way, through the rear beam, through exit blocks then to breakaway cleats which are mounted on the front of the rear beam which are easily accesible. I like this system. I think I have some pics I can post. However, I have never used the nacra style rudders but I have used the dotan system which seems to work nice, but I don't like the rudders which come with the system.

BTW... almost any sailmaker will do tramp repairs/adjustments for you.