I am not an astronaut and I don't understand much the irritium or irridum..
here is my set up:
used iphone 4 (dedicated to the bike) : 40 USD
ram mount: 15 USD
Navigon: Europe 44, morocco, USA: free..
waterproof case: 12 USD
Total: 67 USD.
maps are downloaded offline. so you don't need data or anything else except your GPS signal..
I love my set up...traveled in europe last summer using it last and will be using it again this summer for another tour in europe...
Zuma cost : 550 USD - 67 USD = 483 USD
for 483 USD I bought:
givi V35 + rack for 320 USD
galfer brake lines (both front and rear): 50 USD
Kyruaky highway pegs : 63 USD
currently in Paris with my wife
where we went to a good restaurant for 50 USD
this is what I made out of the zumo cost