My own personal opinion here, GPS companies (Add Name Here) gouge the crap outta their customers just to make a unit waterproof and enlarge some buttons. I mean holy crap, you can buy an upper level car unit for $350.00 that has all the bells and whistles. Then if you want a GPS that has half the funtionality but had Big buttons and is waterproof they get you for $650-$800.00 bucks or even more! BS~! I have the Garmin Nuvi 1350T I paid $135.00 for 2 years ago. I have been in the rain, sun, fog, cold and heat! Never a problem. I do cover it if I can but it has survived several rain storms with not a glitch.
I would love to have a GPS made for biking but I cant justify the cost when I can buy 4 or more auto styles for the same price. Just my 2 Cents worth.