You can also get digital scales at almost anywhere that sells kitchen supplies. Usually they are only good to the gram, but you shouldn't really need any more accuracy then that.
I personally don't even bother with an incubater for cresteds. Most of the info you read indicates that "room" temp is fine, and that fluctuating temps seem to produce stronger hatchlings. Being that cresteds can be a more heat sensitive species I really can't see too much benefit in using an incubator other then to circulate the air and trap a little more ambient humidity. Usually if you have the proper micro environment in the container they are incubating in, and check them regularly, you can maintain the proper environment without an incubator quite easily.
Right now the room I have our eggs incubating in fluctuates 68 at night and 72 during the day, and the hatchlings are taking close to 100 days to hatch. It's a much longer wait, but the 16 hatchlings we are currently taking care of keep us company in the meantime!

That's too bad to hear about the other egg! Sometimes you gotta chalk the first season up to a learning experience and keep improving your methods. Keep asking questions and you'll get it sorted out!