If you want to use the device for route planning, then you are going to have to spend more.
The cycle specific ones are more expensive though than walking one in the basic form
However as you add features the price again rises
The mapping is motor based, unless you pay for the Edge and the Ordnace Survey options (not all systems use OS)
The Garmin ETrex can be picked up with mapping for less than £100 however route planning is rudimentary, it is not until you get to the Edge / Bryton Rider 60 standard that you get postcode routing. Even then this is really a derivation of the motoring algorithms, so can give some weird options.
Finally syncing.
Again you pay for the additional services like Bluetooth, making syncing easier, but very few (if any) will sync directly with Srava, without syncing to a computer / smartphone first.
The 810 for instance automatically updates to my iPhone which then automatically updates to Garmin Connect