Tandem Cycling - Altimeter?

Looking for an inexpensive altimeter for the bike, can be worn on the wrist. Any thoughts?

Polar makes several models. You could probably pick up a used S710 on eBay for cheap. I'm sure there's other models as well.

Garmin 305. Can be had on Ebay, sub $150, and gives you GPS capability as well.

I use a CicloMaster 4.4A (http://www.ciclosport.de/statische/contentframe.php4?frameid=42&content=shop%2Cid%3D958%2C0%2C0%2C2&return=..%2Fstatische%2Fcontentframe.php4%3Fframeid%3D42%26content%3Dshop%252Ccategory%253D18%252C0% 252C0%252C5&sessionid=1984493806) on all my bikes. It doesn't give the feature of wearable on the wrist, but because it is integrated into the bike computer, it can compute the current gradient (which is actually surprisingly sensitive and accurate most of the time). It does have an off-bike mode to be used as just an altimeter and clock, but you'd have to keep it in your pocket.

Timex sells some "adventure" watches with altimeter/barometer and other functions. (The thermometer seems to be very influenced by body heat.)
Campmor has one on sale, "while they last", for $59.97.
Easy to wear on the wrist, but no coordination with any other bike electronics.

I like the Timex price at Campmor and I like the gradient mode on the Ciclomaster. Thanks all for these tips.

I use the Trek Incite ACH puters on all my bikes. Wireless but not digital. Altitude, grade and all the other stuff.