I had considered linking when I made the original post but then reconsidered when I realized that simply typing "bike computer with c" caused Google to autofill the last few letters of the search, and pop up with both a $45 deal on a CatEye computer with cadence, and lower down a Garmin 25. It seemed silly to become a proxy for a highly available and spot on relevant search engine. At best my linking to search results would rob the OP of the context this search could provide. My response was to offer some advice that a simple search would not immediately reveal, and hopefully it was helpful. But I never intended to simply be a replacement for a search engine.

I've had a few CatEye computers over the years, with and without cadence. These are simple devices. They don't do a whole lot more than a digital watch from 1978. They're all overpriced for the technology they embody. But the cheapest one Google finds you with cadence and waterproofing will be just fine. And that quick search I did revealed $45 is about where they start. More in depth searches may find even cheaper off-brand, and they may be fine too. Look at the CatEye website for feature comparisons. Any cycling computer that does cadence will also do speed, distance, time, and a few other things. The technology is so simple there really can't be a terrible one.