Welcome!  Hopefully these pages will make it easier to order the openaltimeter and other items.
Now Here: Updated MS5611 Sensor OpenAltimeter

openaltimeter classic:
"The openaltimeter is a small, lightweight, low-power logging altimeter with an optional built-in LiPo regulator and a very loud beeper! It's aimed at radio-controlled glider pilots, particularly DLG fliers, but because the firmware is open-source it can be customised completely for other applications."   Check out the openaltimeter web site for more information.
FTDI USB->Serial adapter
Now Here! - FTDI +3V/+5V  USB->Serial interface board. This board is compatible with the standard FTDI board used to download/modify setting on the OA, but is half the price!  Has the DTR pin available on the 6 pin interface, so it will reboot the OA (or other Arduino boards).  Has a selectable 3.3V / 5V jumper to set the voltage level.  Please set this to 3.3V before using with the openaltimeter. 
Voltage Dispalys
Various Voltage displays to quickly see how your battery is doing!  Two styles:  weatherproof enclosed voltage display, good for checking your battery or plugging into your switch jack, and small lightweight 3 digit digital displays