If you decide to use 64k bytes rather than 512k for your data-logger, we
have built a similar device and due to pricing breaks we have a few spare
unpopulated PCBs.  The PCB measures about 25mm x 25mm x 1.5mm and is
designed to take the surface mount 16LC84 and up to eight 24LC65 64kbit
IIC eeproms.  The whole thing is powered from a lithium cell.

If you are interested we could come to some arrangement about selling on
some PCBs.

Ben Heller
Department of Medical Physics, Royal Hallamshire Hospital, Sheffield