Why hasn't anyone realised that if you break the PokeWalker you won't lose your Pokemon?! They wouldn't make it like that.
It'll work through Imprinting; When you Transfer your Pokemon to the PokeWalker it'll still be on your HeartGold/SoulSilver game but it'll be put in a un-viewable storage box in the PW Menu and be disabled on the main game until the imprint returns.
Whilst walking around your Pokemon's basic Information [Levels/Experience which'll actually mean nothing on the actual PW, only on the Game it will be important, on th PW it'll just be numbers] will be updated. When you want your Pokemon to 'return' [be un-disabled is a better term], your DS will search for the PW not vice versa, via the in-game PW Menu, as the PW isn't capable of that and your DS will register the codes sent by the infra-red system to the Pokemon, updating it - Think of it like the Action Replay, as it is basically doing the same thing.
If the PW's Screen isn't showing any image/ the PW is cracked/ the PW's Screen is Cracked, you'll still be able to get your Pokemon back- As the only part of real importance on the PW is the infra-red system and that would only break if you purposely break it yourself.
Edit- Oh, and the PokeWalker uses Watch Batteries, which last for years and can be easily replaced; Gamestation and possibly Watch Retailers would replace the batteries for you. At a Price, but it shouldn't be too expensive.