I would like to build a rowing performance device similar to a SpeedCoach produced by Nielsen-Kellerman.

The feature set for these devices includes the following:

Accelerometer

GPS

Sparkfun recently released a $16 GPS receiver, but unfortunately it is currently sold out. Alternatively, in Sparkfun's GPS Tracking Comparisons tutorial the receiver with the best results was Trimble's Corpernicus II, which can be purchased on a breakout board for $75.

Display

Selecting a display setup may be the most complicated component to select. Touch provides no benefit since the device will have to run within a waterproof enclosure. Also, an interesting alternative may be to use a small number of alphanumeric LED displays that each display one character.