pricing about user

There are only 2 prices - free and the one you quoted. There is no premium fee for a developer/Admin type person. Anyone with a free licence can do most of the modelling. The charge comes in when you want to have control over sharing. This is a great model as it is easy (and free) to get started, and as soon as you get into more advanced sharing (e.g. Different content with different people) you pay - and this is where most of the value is extracted too. Anyone that wants to share using the pro features or wants to receive via the pro features must have a pro licence.  

Frankly it is dirt cheap anyway - nothing else comes close on price/value