I'm currently building a new house on a decent sized area and the eventual plan is to build more houses on the land? For this reason I am going to put in pipes, ducts etc. for future use but cover them for time being. Is there a cheap handheld GPS that would give me a reasonably accurate position and make plotting them and finding them at a later date easier?

I'm based in the UK but can get things delivered to an address is the US if anyone has any specific recommendations.

Thanks

Westers