The range is very wide, quite hard to give a quote. More work costs more money. Sometimes it's obvious what takes more work, other times not. The most an animation has ever cost is $2000. I usually let people tell me their idea and we work from there. We go back and forth getting it to a nice workload/budget.

I like to work with my own models, but I can work with existing ones as long as they're not stolen models from games or from a childrens show or something creepy like that.