I'm not sure about your arboricultural background, but I would be leary about doing the work yourself if you are a beginner...... especially if you are going to be spurring the trees yourself. Even if the trees are 30', that is still high enough for you to fall to your death. Just something to think about. Yes, hiring an arborist will cost more than doing it yourself, but they have the insurance to cover them if something were to go wrong............would you, if a tree fell the wrong way?
If you are just new to the site and are an experienced arborist, ignore my gibberish!