A good quality bivy is not cheap!

As for condensation, if your sleeping bag has dry-loft material on the outside, the condensation is quite easily shaken off in the morning.

I use an OR Basic Bivy. Once you add all the hoops and stuff, the cost and weight are not worth the inconvience, compared to a tent. My bivy is much more compact than my tent which is a real advantage if I want to do a shorter trip with my smaller pack.