The cheapest GENUINE TomTom maps I've found are those designed for PDAs. I have a GO 730 and just bought a TT sealed, boxed 'kit' with Navigator 6 and all the USA & Canada maps.
Most people will say they can't be used on a TT Go, One or XL etc. but they definitely can! Mine cost ?19.95. It's a touch tricky to install but you have the option of state-by-state maps to keep the file space lower, or the entire North America map. A basic sattelite view is also an option. As you have to install Navigator 6 it might be easier to creat a new User Account in WIndows and do it from there so it won't conflict with TT Home 2.7, or whatever you use for main updates etc. Get yourself a 2GB SD card and keep it seperate from your other maps if you like. You can install any map options through Navigator 6.
Most people will say they can't be used on a TT Go, One or XL etc. but they definitely can! Mine cost ?19.95. It's a touch tricky to install but you have the option of state-by-state maps to keep the file space lower, or the entire North America map. A basic sattelite view is also an option. As you have to install Navigator 6 it might be easier to creat a new User Account in WIndows and do it from there so it won't conflict with TT Home 2.7, or whatever you use for main updates etc. Get yourself a 2GB SD card and keep it seperate from your other maps if you like. You can install any map options through Navigator 6.