You can get Magene sensors for under $35 from Amazon. They work with phone apps. You don't need cell coverage to use the sensors. They communicate with your phone over the Bluetooth interface.

I run "Cyclemeter" on my phone. Costs $10 per year and does exactly what I want.

I use a bar mount to hold my phone. Mine is made of aluminum and came off of eBay. They are cheap. Just be sure that the mount you get has long enough fingers to hold your phone or your phone case.

All told, it should run you about $60.00 for sensors, mount for phone, and software.