I had two cateye strada cycle computers sitting in a tub, collecting dust in my closet for the last year. I went to put one of them on my new bike and I couldn't find either magnet.

After cursing for a day and checking the fridge a few times I ended up finding them stuck to bottom of an old saddle! Crisis averted... just before I sprung for a Garmin cadence/speed sensor that would interface with my Oregon GPSr. I'm still considering it, since I thought it might be fun to record my route from time to time. Anyone have any experiences with the Garmin?

No but you can always save $500 by just remembering your route and plotting it on https://www.bikemap.net/. That's what I like to do (sorry can't buy an accessory worth half my bike )

I already have the expensive part: the Oregon (avid geocacher). I was looking at the cadence/speed sensor that interfaces with it wirelessly. And with the way I'm going... the GPSr amounts to about 1/4 of the price of my bike...

The Oregon can pair with a Cadence/Speed sensor?

Every now and then it'll tell you that you just rode 4,000 miles. It understands cadence, but won't take speed and distance from the sensor, so you can't avoid these sorts of errors. If they bother you, the Oregon shouldn't replace your Cateye.

But the elevation plot feature is really nice, and if you do loops, or follow a GPX route someone gave you, it can help you pace yourself very well. All in all it works very well as a bike computer, and it's very nice to be able to make charts and maps when you're done - if you're a data person. If you don't already have the heart rate monitor, you'll eventually want that, too.

This is well worth the $10:

I use my Android smart phone as my bike computer with this app.

It doesn't record cadence, of course. My bike computer needs are simple.
It does record a KML file that you can load directly into Google Earth or Google maps.