My team is also trying to branch out with our use of sensors. After tons of begging and fundraising, I convinced my team to buy
one of these (the analogue version). It's perfect. Our team's autonomous and even teleop relied significantly on this, and it hasn't ever failed us. Also, I've heard from other teams that
these are very decent encoders (and are easy to mount), and they work with the encoder classes provided by FIRST with the programming software.