A dip tube is closer to $10 or $15. I can't remember what I last spent, but they might even be cheaper than that.
The only problem with taking out a dip tube is that you probably have to lie the water heater down. Draining it is easy enough, once you let it cool down. I'm surprised it's soldered in. Around here, there's always a flexible metal connector from the valves to the nipples. If it's really soldered and there's no other way, then you know for yourself whether you can do it. For under $50, you can get a nice little torch with MAPP gas and everything you need to do the job. Check with your local Home Depot or Lowes to see if they have some weekend seminar on soldering pipes. That's assuming that you can't add a flexible connector, which you may be able to do.
The labor is about the same to replace the dip tube or change the water heater, short of actually moving it around. Once the water lines are disconnected, the dip tube (or what's left of it) often just lifts out. Some come attached to the nipple, and the nipple must be replaced.
Another thing is that the price seems way high, unless there's something about the job you are not telling us.