Sounds like you are off to a good start, fenders will make things much more comfortable when it rains for sure. If you are lucky enough to have a bike shop that deals with used bikes and has a good selection that is a good place to start because you can test ride a few and see what feels best. You can certainly find a nice quality bike for that price range, good hybrids are harder to find used than mountain bikes but they are out there.

If you want to make sure you get quality, buy brands you would usually see in bike shops (Giant, Trek, Specialized, etc) Another advantage if you have a shop who sells used stuff is a good shop will do a full tune up before it leaves so you should be good to go for a while

Have fun and enjoy the ride.