No - HFD - the GPS I mentioned works very well in shirt pocket AND works indoors (house - not industrial unit made of steel).
It takes a minute or two to grab the satellites (20 channel) but once it's got them the thing is brilliant. WAAS enabled, too (it says).
Excellent bit of kit and a colleague at the CAA has the exact same model (also driving tomtom and memory map on his own pda, as do I and Chinchilla).
Truly - brilliant piece of kit (and VERY small). GPS came with car battery lead and mains lead for charging. Have never run a battery flat yet - have used non-stop for over six hours (especially when I forget to turn it off 'cause it's in my shirt pocket).
GPS cost me US$68 (just under £45?) on ebay - including delivery.