HP
You can get brand new compasses direct from the manufacturers if you need accuracy, but I guess you won't be too bothered navigating with them. They do look gorgeous though! If you pick up some old stock that need overhaul, dont get the luminous version. You need radioactive material certificates up the ying-yang to open them and deal with the radium paint. I seem to recall Guy Black has the contacts for this. Didn't Tim Moore have a stash of P.11's in overhauled condition?
You can get virtually all the Gosport systems in new or near new condition for a reasonable price, don't settle for anything too ropey.
Drop me an e-mail or give me a bell if you need anymore info.
ATB
ExO